You'll be asked to confirm the action. To do so, simply type "y".
If you're not following this procedure, the session will stay open in the background until you manually kill it using Activity Monitor or by using the "kill" command.
Here's some information on macOS' built-in "screen" command, which is used by our iTerm2 plugin for serial port connections:
Tags: OSXFAQ Serial Port COM screen iTerm2 iTerm Terminal