You mean 5n?
The "n" represents a variable. This means that "n" can be any number that ever existed. It's just that the problem is not specific enough to give you the exact number. And since we don't know what that number is, we are replacing it with a letter, which is "n" in this case.
You can see that the "n" is very close to the 5. This means that n is being multiplied to 5. "5n" is the exact same thing as "5 * n".
