Mother bought me a hat. What does top mean in this sentence?

Mother bought me a hat. At the top here is a quantifier. In other words, it means hat. Because our country has a rich vocabulary. Different items have different sayings. When I say riding a bike, we can say it is a car. A cow, a sheep, a child, a road and so on.

These corresponding quantifiers are all different, which are different in language environment and need to be expressed by different words.

When you get to middle school, you will learn this knowledge, and gradually you will understand and use it.