Answer: The judicial branch is a branch of the United States government that contains the court system. The courts review and explain laws, as well as handling legal cases when laws are broken, such as destruction of property, and when lawsuits happen, such as a person sues a company or individual for perceived wrong-doings.
There are 3 levels:
District Courts (the trial court)
Circuit Courts (the first level of appeal)
The Supreme Court of The United States (the final level of appeal in the federal system)
(An appeal is when you go to a higher court and try to reverse the decision of the lower court)
If there are any parts of this definition that were unclear, or you need further points explained, feel free to comment on it, and I'll try my best to help, if I'm able to and available at that time.
I hope this helps in some way!