If you can easily slap the ceiling with the palm of your hand, you're tall. The measure of your height tells you exactly how tall you are.
You don't have to be tall to be a good basketball player, but it can come in handy when you're trying to get the ball in the basket. When it's not describing a person's stature, the adjective tall might refer to a beverage, like a tall glass of lemonade. A tall tale is an outlandish, hard-to-believe story, and a tall order is a really unreasonable request. And when you stand tall, you act confidently.