Difficult Question to Understand (Computer Artitechture)
Well, as binary typically goes, one bit represents two possible values: 0 and 1. With two bits there are a possible combination of four values: 0, 1, 2, 3 in hex/decimal/octal or 00, 01, 10, 11 in binary. Expand out to three bits you have eight values. 0 to 7 or 000, 001, 010, 011, 100, 101, 110, and 111. 

Expand upon this and you'll have your understanding. 

For reference (with a nice animation for counting on any base): https://www.mathsisfun.com/binary-number-system.html