When someone selles something, they give it to someone else in exchange for money.
Selling things is a normal and important part of business and life.
Examples:
She selles her old toys at the market.
He selles his car to buy a new one.
The store selles many different kinds of food.
He selles his bike for a lot of money.
She selles her paintings to people all over the world.
He selles his house and moves to a new one.