Sexual arousal is when someone's body and mind feel excited and interested in something they find sexually attractive (like someone they find attractive, or a sexual activity they enjoy).
When you feel sexually aroused, your body might show signs like your heart beating faster, your breathing speeding up, your skin feeling warmer, and your genitals (private parts) becoming more sensitive. Sometimes, people might also feel a tingling or "fluttery" sensation in their stomach, or even shaky or weak.
It's important to remember that sexual arousal is a natural and normal part of being human, and it's nothing to be ashamed or embarrassed about. But it's also important to understand that not everyone experiences sexual arousal in the same way or at the same time-- it's a really personal and individual thing!