During Vim editing, We must have to delete unnecessary trailing whitespace which make code easy to read or merge.
So you can add .vimrc file in /YOUR_HOME_PATH/
$ cd
$ vim .vimrc
Add below contents then save and exit.
hi Whitespace ctermbg=darkred guibg=darkcyan
autocmd BufEnter * if &ft != 'help' | match Whitespace /\s\+$/ | endif
autocmd BufEnter * if &ft == 'help' | match none /\s\+$/ | endif
Enjoy it.
Reference : vim 顯示多餘空白( trailing whitespace )