How do you determine how much money an address has? If you get an address, and have payments sent to you, how are people able to determine how much money you have? What steps do they do to figure this out?
They don't.

You can have as many addresses as you like, and there is little anyone can do to track them all to you.

This means that usually people can know how much money a single address has, but that's pointless, since you can have multiple addresses.