In this scene, Chris Gardner (played by Will Smith) tells his son that he should not set his sights too high with basketball. He crushes his dream of one day playing professional basketball. What happens next is something that more parents need to tell their children.
Don't ever let somebody tell you... You can't do something. Not even me. You got a dream... You gotta protect it. People can't do something themselves, they wanna tell you you can't do it. If you want something, go get it. Period.