How to create a multi column multi row table without borders in LaTeX?

documentclass[11pt]{article}
usepackage{graphicx}

begin{document}
  This a multirow and multicolumn table
    begin{tabular}{|c|c|c|}
      hline
       a & b & g
       hline
       b & c & h
       hline
       g & v & a
       hline
   end{tabular}

end{document}

The | represent the vertical lines separating each element of the cell and c is the option to centre the cell's content (there are others like r -> right and l -> left).

Finally hline stands for horizontal line. I hope I was clear enough.

You have to compile at least twice with every change in the percentage (last) column (since it uses eqparbox for getting the appropriate alignment).

documentclass{book}

usepackage[
  margin=1in,
  landscape
]{geometry} % Just for this example

usepackage{booktabs,collcell,eqparbox,makecell}


begin{document}

begin{table}
  centering
  newcommand{pa}[1]{eqmakebox[CFNetvsNeuMF][r]{#1}}% Percentage alignment
  newcommand{hlc}{textbf}% Highlight cell
  caption{Comparison results of different methods in terms of NDCG@10 and HR@10.}
  begin{tabular}{ *{9}{c} >{collectcellpa}c<{endcollectcell} }
    toprule
    &
    &
    multicolumn{4}{c}{Existing methods} &
    multicolumn{3}{c}{CFNet} &
    
    cmidrule(lr){3-6}cmidrule(lr){7-9}
    Dataset & % raisebox{.7normalbaselineskip}[0pt][0pt]{Dataset}
    Measures & % raisebox{.7normalbaselineskip}[0pt][0pt]{Measures}
    ItemPop & eALS & DMF & NeuMF &
    CFNet-rl & CFNet-ml & CFNet &
    multicolumn{1}{c}{smash{makecell[b]{Improvement of  CFNet emph{vs.} NeuMF}}} 
    midrule
    ml-1m &  HR  & 0.4535 & 0.7018 & 0.6565 & hlc{0.7210} &
      0.7127 & 0.7073 & hlc{0.7253} &
      0.6% 
          & NDCG & 0.2542 & 0.4280 & 0.3761 & hlc{0.4387} &
      0.4336 & 0.4264 & hlc{0.4416} &
      0.7% 
    addlinespace
    lastfm &  HR  & 0.6628 & 0.8265 & 0.8840 & hlc{0.8868} &
      0.8840 & 0.8834 & hlc{0.8995} &
      1.4% 
           & NDCG & 0.3862 & 0.5162 & 0.5804 & hlc{0.6007} &
      0.6001 & 0.5919 & hlc{0.6186} &
      3.0% 
    addlinespace
    AMusic &  HR  & 0.2483 & 0.3711 & 0.3744 & 0.3891 &
      0.3947 & hlc{0.4071} & hlc{0.4116} &
      5.8% 
           & NDCG & 0.1304 & 0.2352 & 0.2149 & 0.2391 &
      hlc{0.2504} & 0.2420 & hlc{0.2601} &
      8.8% 
    addlinespace
    AToy &  HR  & 0.2840 & 0.3717 & 0.3535 & 0.3650 &
      0.3746 & hlc{0.3931} & hlc{0.4150} &
      13.7% 
         & NDCG & 0.1518 & hlc{0.2434} & 0.2016 & 0.2155 &
      0.2271 & 0.2293 & hlc{0.2513} &
      16.6% 
    bottomrule
  end{tabular}
end{table}

end{document}

With use of the siunitx package:

documentclass{book}
usepackage[landscape]{geometry} 
usepackage{booktabs, makecell, multirow}
% new
usepackage{siunitx}
usepackage{etoolbox}
newrobustcmdB{DeclareFontSeriesDefault[rm]{bf}{b}bfseries}
usepackage{xparse}
NewExpandableDocumentCommandmcc{O{1}m}
    {multicolumn{#1}{c}{#2}}


begin{document}
    begin{table}
    centering
    sisetup{detect-weight,
             mode=text,
             table-format=1.4}
    setlengthtabcolsep{0pt}
    caption{Comparison results of different methods in terms of NDCG@10 and HR@10.}
  begin{tabular*}{linewidth}{@{extracolsep{fill}}
                               l c 
                          *{7}{S} 
                               S[table-format=2.1,
                                 table-space-text-post=%]<{%} }
    toprule
    &   & mcc[4]{Existing methods} 
            & mcc[3]{CFNet} 
                &  mcc{multirow{2}{*}{makecell{Improvement of  
                                              CFNet emph{vs.} NeuMF}}} 
    cmidrule(lr){3-6}cmidrule(lr){7-9}
Dataset & Measures  
        & {ItemPop} & {eALS}    & {DMF}     & {NeuMF} 
        & {CFNet-rl}& {CFNet-ml}& {CFNet}   & mcc{}        
    midrule
 ml-1m  &  HR       
        & 0.4535    & 0.7018    & 0.6565    &B 0.7210  
        & 0.7127    & 0.7073    &B 0.7253  &   0.6         cr
        & NDCG      
        & 0.2542    & 0.4280    & 0.3761    &B 0.4387  
        & 0.4336    & 0.4264    &B 0.4416  &   0.7         cr
    addlinespace
lastfm  &  HR  
        & 0.6628    & 0.8265    & 0.8840    &B 0.8868
        & 0.8840    & 0.8834    &B 0.8995  &   1.4         cr
        & NDCG 
        & 0.3862    & 0.5162    & 0.5804    &B 0.6007  
        & 0.6001    & 0.5919    &B 0.6186  & 3.0           cr
    addlinespace
AMusic  &  HR  
        & 0.2483    & 0.3711    & 0.3744    & 0.3891 
        & 0.3947    &B 0.4071  &B 0.4116  &   5.8         cr
        & NDCG 
        & 0.1304    & 0.2352    & 0.2149    & 0.2391 
        &B 0.2504  & 0.2420    &B 0.2601  &   8.8         cr
    addlinespace
AToy    &  HR  
        & 0.2840    & 0.3717    & 0.3535    & 0.3650 
        & 0.3746    &B 0.3931  &B 0.4150  & 13.7          cr
        & NDCG 
        & 0.1518    &B 0.2434  & 0.2016    & 0.2155 
        & 0.2271    & 0.2293    &B 0.2513  &   16.6        cr
    bottomrule
  end{tabular*}
end{table}

end{document}