What does it mean I got hard?

I was in class and this girl a couple years older than me was helping this guy I talk to in class. I looked at her and saw her roll her her shirt so it showed her stomach and belly ring. I instantly got an erection. Does it mean I have a crush on her, am attracted to her, or like her, or I got turned on? It was instant
Answers

pit bulls bite

likely the belly ring turns you on

Josie

You have hit puberty.

balan

It means that all sexual organs are working perfectly .Such erections are common among teenagers.Enjoy.Regards..