These are anal beads. They're loads of fun! You can stick them all up your ass and feel nice and full, then pull them out one at a time, or all at once. You can feel nice and stuffed, without having to worry about fitting in a huge dildo.
The best things to stick up your ass are like that. If you put a bunch of small things up your ass, you don't have to worry about getting them stuck like you would with one giant thing.
They also have a string you can use to pull them out. If you decide to insert something bigger, you can tie a string around it, and test it to make sure it is 100% secure, then insert it. Still be careful about anything too big, so you don't tear something.