Wushu is a type of martial arts that comes from China. People who practice wushu use their arms and legs to do special movements and techniques. In wushu, there are many different ways to move your arms, but one type of wushu is called "eighteen arms."
Think about how you use your arms and hands for different things. You might use them to write, eat, or throw a ball. In wushu, there are 18 specific ways that you use your arms and hands to fight or defend yourself. These movements are called "arms" because they involve your arms and hands.
Some of the "arms" in wushu include things like a punch, a slap, a grab, and a block. Each "arm" has its own name and special way of being done. For example, the "fist" arm is done by making a tight fist with your hand and punching straight ahead.
When someone is practicing wushu using the "eighteen arms," they will move their arms and hands in different ways to show off their strength, speed, and skill. It's like doing a dance, but instead of using your feet, you use your arms and hands.
So that's a simple explanation of the "eighteen arms" in wushu – they're 18 specific ways to use your arms and hands in this type of Chinese martial art.