When you block someone on yubo all the content you shared together is removed. They will also not be able to find your profile or watch your live video.
If you want to report some inappropriate behavior, make sure to take screenshots before blocking the profile otherwise you will not be able to provide proof or any abuse you may have suffered.
It is really easy to block a user. Watch the video here:
If you want to unblock someone, watch this video to know how to do it: