Answer:
It's kind of like an extra amount of information about the noun. An example: "That girl who is typing super fast is my sister". I added information that didn't need to be known, but, it adds more information about the noun. So to find it, you'll notice that they have things that don't necessarily need to be in the sentence. (These will have relative pronouns like "who, whom, which, that, whose... or there will be relative adverbs like "when, where, or why")
I'll give you a few more examples.
For my birthday, my mom is baking me cupcakes, which I really love.
My dad likes to remind me of the days he was a kid, when there were no computers.
My grandma is a great person, of whom always makes food for her guests.
I hope those help!
Step-by-step explanation: