No winner?

There are no winners, I think you lose a giveaway slot.

You can reuse the key (obviously) but you manually need to set up a new giveaway if you want to give it another go.

If no one entered then you get the GA slot back. The key is unused and you can redo it if you wish or create a different group or lower GA so you do get entries. I've had a couple like that.

ok i'll enter, just because you might not be a multi account botter.

I see you're quite new here and you're doing your first giveaway. Congratulations !
Don't worry, if there's no winner, there's no winner and that's all. But as your GA has no restrictions, my guess is that you'll get some entries from bots people.
Edit : The time, I found how too strike a word, you already have 20 entries !

you won't really need to worry about no entrants unless you are running something that is super common(payday 2 for example) with a higher lvl requirement or GA's in small groups.

unrestricted lvl 0 GA's will always get people? entering.

You do need 5 entries for CV to count (but if you do public giveaways you shouldn't be encountering that unless for some vague DLC).

Yeah, you can just run the GA again. I'm in a reasonably small group that has a monthly giveaway requirement, and sometimes my GAs have received no entries. When that happens, I just copy and paste the key into a new GA that's public, and it gets hundreds of entries, or more.