Okay, so you know how there are some people who believe in Jesus and some people who believe in God, right? Well, there are also some people who believe in both Jesus and God, but they also follow some of the Jewish customs and traditions.
These people are called Messianic Jews. They believe that Jesus is the messiah that the Jewish people have been waiting for, but they still keep some of the Jewish traditions like celebrating the Sabbath on Saturday and keeping kosher (eating only certain foods).
It's kind of like combining two things that you love, like if you love pizza and ice cream, you might want to try eating them together (although that might not taste very good!).
Some people who are Jewish might not agree with the idea of believing in Jesus, so it can be a controversial topic. But for Messianic Jews, it's a way to connect with both their Jewish heritage and their faith in Jesus.