I began using IdeaVim plugin for Android Studio, some time ago. It's nice, but as a Vim newbie, I wasn't aware that Vim doesn't use system (Windows, macOS, XWindow, etc.) clipboard for copy/paste by default. So when you use y command in IdeaVim, it doesn't paste to other applications..

The solution is easy when you spot it: Your ~/.ideavimrc file needs the following line

set clipboard+=unnamed