The info popup just says "Enables multiple players. Can be toggled during a game"

I think it is a multiplayer option, isn't it?

Yes.

Ok, thanks mate. I really hope multiplayer will come soon, it ll be amazing

Pass and play is multiplayer mode with one device. Multidevice will come eventually.

Try it out. It kind of emulates playing "closed hand" in the table-top version. Essentially where no one can see what cards you have.

 

It's sometime beneficial in the table top version to stop certain types of people (you know who you are) from taking over the game and trying to tell everyone how to play and what cards to play.