How can I have two bar charts side by side

I guess that you looking for something like this:

(red lines indicate page layout)

Unfortunately your question as well answer are not entirely clear and erroneous (misses are packages, closing braces, ...). Consequently the most of code in my MWE is written from scratch. See, if can help you:

documentclass{article}
usepackage[demo]{graphicx} 
usepackage[strict]{changepage}
usepackage{pgfplots}
pgfplotsset{compat=1.17}

usepackage{subcaption}
%---------------- show page layout. don't use in a real document!
usepackage{showframe}
renewcommandShowFrameLinethickness{0.15pt}
renewcommand*ShowFrameColor{color{red}}
%---------------------------------------------------------------%


begin{document}
    begin{figure}[!ht]
    centering
pgfplotsset{
    width=5.6cm, height=7.0cm,
    xbar,
    enlarge y limits=0.1,
    enlarge x limits={0.3,upper},
    ytick=data,
    nodes near coords, nodes near coords align={horizontal},
    %every node near coord/.append style={font=tiny},
            }
begin{tikzpicture}
    begin{axis}[
xlabel={(a)},
symbolic y coords={A, B, C, D, E, F},
                ]
addplot coordinates {(35,A) (24,B) (23,C) (21,D) (19,E) (17,F)};
    end{axis}
end{tikzpicture}
    hfil
begin{tikzpicture}
    begin{axis}[    
xlabel={(b)},
symbolic y coords={A1, A2, A3, A4, A5, A6},
                ]
addplot coordinates {(63,A6) (53,A5) (16,A4) (14,A3) (9,A2) (8,A1)};
    end{axis}
end{tikzpicture}
    caption{An overview on of side by side bar charts}
label{fig}
    end{figure}

    begin{figure}[!ht]
pgfplotsset{
    width=5.6cm, height=7.0cm,
    xbar,
    enlarge y limits=0.1,
    enlarge x limits={0.3,upper},
    ytick=data,
    nodes near coords, nodes near coords align={horizontal},
        xbar,
    enlarge y limits=0.1,
    enlarge x limits={0.3,upper},
    ytick=data,
    nodes near coords, nodes near coords align={horizontal},
            }
begin{adjustwidth}{}{-dimexprmarginparwidth+marginparsep}
    begin{subfigure}{0.35linewidth}
begin{tikzpicture}
    begin{axis}[
xlabel={(a)},
symbolic y coords={F, E, D, C, B, A },
                ]
addplot coordinates {(35,A) (24,B) (23,C) (21,D) (19,E) (17,F)};
    end{axis}
end{tikzpicture}
    caption{SubCaption1}
    label{fig:subim1}
end{subfigure}
    hfill
begin{subfigure}{0.28linewidth}
includegraphics[width=linewidth, height=5.6cm]{mesh}
vspace{baselineskip}
    caption{SubCaption2}
    label{fig:subim2}
end{subfigure}
    hfill
begin{subfigure}{0.35linewidth}
begin{tikzpicture}
    begin{axis}[
xlabel={(b)},
symbolic y coords={A1, A2, A3, A4, A5, A6},
                ]
addplot coordinates {(63,A6) (53,A5) (16,A4) (14,A3) (9,A2) (8,A1)};
    end{axis}
end{tikzpicture}
    caption{SubCaption3}
    label{fig:subim3}
end{subfigure}
    caption{Caption for this figure with two images}
    label{fig:image2}
end{adjustwidth}
    end{figure}
end{document}

documentclass{article}
usepackage{amssymb}
usepackage{graphicx}
usepackage{tikz}
usetikzlibrary{shapes.geometric,arrows}
usepackage{pgfplots}
usepackage[colorinlistoftodos,prependcaption,textsize=tiny
begin{document}




begin{figure}[!h]

begin{centering}
%begin{adjustwidth}{-1.5cm}{}
begin{tikzpicture}  
begin{axis}[
    %tiny,
    xbar, 
    width=5.6cm, height=7.0cm, 
    enlarge y limits=0.01,
    enlargelimits=0.07,  
    xlabel={(a)},
    symbolic y coords={F, E, D, C, B, A },
    ytick=data,
    nodes near coords, nodes near coords align={horizontal},
    %every node near coord/.append style={font=tiny},
]
    addplot coordinates {(35,A) (24,B) (23,C) (21,D) (19,E) (17,F)};
end{axis}
end{tikzpicture}  
begin{tikzpicture}
begin{axis}[
    %tiny,
    xbar, 
    width=5.6cm, height=7.0cm, 
    enlarge y limits=0.01,
    enlargelimits=0.07,  
    xlabel={(b)},
    symbolic y coords={A1, A2, A3, A4, A5, A6},
    ytick=data,
    nodes near coords, nodes near coords align={horizontal},
    %every node near coord/.append style={font=tiny},
]
    addplot coordinates {(63,A6) (53,A5) (16,A4) (14,A3) (9,A2) (8,A1)};
end{axis}
end{tikzpicture}  
caption{An overview on of side by side bar charts}
%end{adjustwidth}
label{fig}
end{centering}
end{figure}

begin{figure}[h]
begin{subfigure}
begin{tikzpicture}  
begin{axis}[
    %tiny,
    xbar, 
    width=5.6cm, height=7.0cm, 
    enlarge y limits=0.01,
    enlargelimits=0.07,  
    xlabel={(a)},
    symbolic y coords={F, E, D, C, B, A },
    ytick=data,
    nodes near coords, nodes near coords align={horizontal},
    %every node near coord/.append style={font=tiny},
]
addplot coordinates {(35,A) (24,B) (23,C) (21,D) (19,E) (17,F)};
end{axis}
end{tikzpicture}   
%caption{Caption1}
%label{fig:subim1}
end{subfigure}
begin{subfigure}
includegraphics[width=0.9linewidth, height=5cm]{mesh}
begin{tikzpicture}
begin{axis}[
    %tiny,
    xbar, 
    width=5.6cm, height=7.0cm, 
    enlarge y limits=0.01,
    enlargelimits=0.07,  
    xlabel={(b)},
    symbolic y coords={A1, A2, A3, A4, A5, A6},
    ytick=data,
    nodes near coords, nodes near coords align={horizontal},
    %every node near coord/.append style={font=tiny},
]
    addplot coordinates {(63,A6) (53,A5) (16,A4) (14,A3) (9,A2) (8,A1)};
end{axis}
end{tikzpicture}  
%caption{Caption 2}
%label{fig:subim2}
end{subfigure}
caption{Caption for this figure with two images}
label{fig:image2}
end{figure}
end{document}