What are school piano pedals for? Explain

We all went to school. And each had a music lesson, which almost always had a piano, which the music teacher sometimes played and taught. For example, for a very long time I was tormented by the question, why are pedals installed on the piano? In addition, when the music teacher played it, he actively pressed these pedals, but I did not hear the difference in sound. What are pedals for? Let me tell you.