it’s steam game which means there’s a key?

Maybe.
If the game is already in your Steam account, no. I can’t seem to run the actual policy down with a quick search, but games in your Steam library are not transferable.
If you have received a key in your email (It’ll be a long, alphanumeric sequence) then you can forward that to someone else, so long as it hasn’t been used by you or anyone else.
If the game was sent as a gift to your Steam account using the Steam gift system. Then no, you cannot transfer it.