I am trying to commit all my changes by using following command
git commit -a
Note : I want to commit without any “commit message”
but when I execute above command it shows me the screen shown below, and I don’t know how to get out of this screen to complete my commit.

You must specify a commit message with each commit. There are two ways to do this. First, you can provide it on the command line, using the
-mswitch:If you don’t specify that switch, git opens the configured editor. By default, this is vim. To write the message in vim, type i to enter insert mode, then type your message. Hit esc to exit insert mode, then type
:wqto save (write) and quit the editor.You can also configure another editor to be used by git. On the command line, you can run a command like
git config --global core.editor notepad, wherenotepadis the name of the editor that you prefer.