What am I supposed to do with copper stub-outs?

Apologies for the really dumb question. I’ve got stub-outs for a new bathroom vanity. They are connected to pex. My friend/plumber also left me two of these shut off valve things. I’m not sure how they are supposed to fit into the copper.

So this is what I’ve been able to figure out so far via googling.

1. Put up drywall so I get the right amount of pipe showing. 2. Cut the copper to the proper length. 3. Use either a sharkbite or a compression shut off valve that also has connections for my water lines.

Am I on the right track?? Can anyone EIL5??

Also, please ignore the drain pipe facing the opposite direction (the bathroom is getting moved to this new location and I haven’t moved that yet). And the galvanized pipes are old and not in use.