Cold reading is when someone pretends to know things about you without actually knowing anything about you beforehand. It's like when you go to a magic show and the magician asks you to think of a number between one and ten, and then they guess the number you thought of. They don't really know what number you picked, but they use clues to make a good guess.
A cold reader might do things like ask you questions about yourself, like your name, birthday, and where you're from, and then use those things to make educated guesses about your life. They might also use body language and tone of voice to make you feel like they're really connecting with you.
Cold reading is often used by people like psychics and fortune tellers to make it seem like they have special powers, but really they're just good at guessing and making general statements that could apply to anyone. It's important to be wary of people who claim to have supernatural abilities, and to remember that cold reading is not real magic.