The original idea was that "planning poker" should estimate the tasks in "story points", which are absolutely NOT supposed to correspond to days. It is just a way of saying "it seems like the task X will require twice as much work as task Y". Some teams do not use numbers at all, and estimate stories in "t-shirt sizes": S, M, L, XL, XXL.
But of course, most companies want to have their Scrum and micromanage it too. So they estimate in days, and call them "story points". Or sometimes they don't even bother to pretend, and estimate directly in days.
(So, how can you estimate how much gets done during the sprint, when all you have is the "story points"? You keep the records from previous sprints, and see how many "story points" got done back then. Adjust the number if someone takes a vacation, etc. This is self-correcting in long term: if someone starts pushing developers to estimate low story points, you will see that fewer story points get done per sprint, so your estimates of how much work gets done will remain correct.)
But of course, most companies want to have their Scrum and micromanage it too. So they estimate in days, and call them "story points". Or sometimes they don't even bother to pretend, and estimate directly in days.
(So, how can you estimate how much gets done during the sprint, when all you have is the "story points"? You keep the records from previous sprints, and see how many "story points" got done back then. Adjust the number if someone takes a vacation, etc. This is self-correcting in long term: if someone starts pushing developers to estimate low story points, you will see that fewer story points get done per sprint, so your estimates of how much work gets done will remain correct.)