Semikhah is a special ceremony that happens in the Jewish religion when someone becomes a rabbi. It's kind of like getting a diploma when you finish school, but it's for becoming a religious leader instead.
During the semikhah ceremony, the person who wants to become a rabbi goes in front of a group of other rabbis who are already very wise and knowledgeable about Jewish teachings. They ask the person lots of questions to make sure they really know their stuff about the Jewish religion.
If the person answers all the questions correctly, the rabbis will give the person a piece of paper, which symbolizes their "diploma" for becoming a rabbi. They also lay their hands on the person's head and bless them, which means they ask for very good things to happen to the new rabbi.
After someone gets semikhah, they can lead their own Jewish community and help people as a spiritual guide. So, it's a really important and special ceremony!