We've all been there, us traditionally windows developers. Occasionally a tool on windows will open Vi, typically when you've not configured git, or you're trying out Linux and experimenting with .NET cross platform.
First - hit esc a few times to make sure you are in Command Mode. Then you want to enter
:q!
This will abandon all changes and quit. If you do want to save your changes, the way to quit is still press esc to get into Command mode and then :
:wq