what is the poke for on FaceBook?

A Facebook poke is a rather simple little feature, that lets one person send a playful nudge to another. It doesn’t carry one fixed meaning, like it just depends, on who sent it and why, basically.

It might mean

They just want to drop a casual “Hi” without typing a full message
They are trying to get your attention, a quick “hey, look here” kind of thing
They’re messing around, joking, or being a bit playful
They might be hoping you’ll respond, and start some sort of chat

A poke, though, doesn’t automatically say “flirting” or confirm any real, special plan. Most times it’s simply a small social tap.

If you get one, you can:
Poke them back, just to show you saw it
Message them, if you actually want to talk
Or ignore it, if it doesn’t feel right for you

So, in short, a Facebook poke is mostly a casual way to get attention, and what it “means” is going to depend on the moment, the context and how you know the person.