Baal teshuva means a person who wasn't always following the Jewish religion and now chooses to start following it. It's sort of like deciding to be more Jewish after not being very involved before.
Imagine you have a toy that you don't always play with, but one day you decide you want to start playing with it more often. That's kind of like what a baal teshuva is doing - they're deciding to be more involved in their religion.
Sometimes, a baal teshuva may have to learn new things about the Jewish religion that they didn't know before. It's like learning new things about your toy - you might not know every trick it can do until you start playing with it more.
Overall, being a baal teshuva means being someone who is choosing to become more involved with their Jewish faith and learning new things about it along the way.