New driver of Seattle. Need help

Hi guys. I’m not too sure if this type of post is allowed, so I apologize in advance.

I just finished Driver’s Ed and I am very excited to get on the road. Tonight, I went freeway night driving with my mom. It was around 10 o’clock, so there was not too much traffic.

After exiting the freeway, I got to this light by Chelan Cafe. It was red at the time, so I stopped because you stop at a red light. However, my mom started scolding me because I shouldn’t have stopped, and there were several cars behind him. I’m so confused why everyone doesn’t stop at this light, even if it’s red. I know you’re allowed to make a right on red, but this specific is confusing me because it’s specifying that this direction must stop. I felt very overwhelmed because my mom was not explaining it well and was just getting mad that I didn’t understand. If anyone can explain to me like I’m 5 why you don’t have to stop at this light even if it’s red, I would be very thankful. Also, sorry if this is a stupid question, I’m just genuinely confused.