How to write the title of my presentation in a block in Beamer using Boadilla Theme

You could add setbeamercolor{title}{...} to the preamble of your document in order to add a colored box with rounded corners and a drop shadow around the title on your title frame. Depending on the shade of blue you want to get, for example one of the three shades already present in the footer, you could use setbeamercolor{title}{parent=author in head/foot} or one of the other two versions shown in the following MWE:

documentclass{beamer}
usetheme{Boadilla}
title{Equivalent forms of LUB Property}
author{Saikat Goswami}

institute[]
{
  Department of Mathematics
   
  Ramakrishna Mission Vidyamandira
   
  Belur Math 
  
  [email protected]
}

date{today} 

setbeamercolor{title}{parent=author in head/foot}
%setbeamercolor{title}{parent=title in head/foot}
%setbeamercolor{title}{parent=date in head/foot}

begin{document}

begin{frame}
maketitle
end{frame}

end{document}

The three versions will result in the following outputs:

---

Please note that I also slightly altered the argument(s) of the institute command in comparison to your original code. I added [] in order to prevent the institute from showing in the footer in which it would partially be hidden by the "title" field. I also added blank lines to make sure, the 4 individual lines in the code are also shown in 4 lines in the resulting pdf file. Lastly, I also removed the inst command, since it is usually used for multiple authors with different affiliations.