16 Different Values
There are 16 Hexadecimal digits. They are the same as the decimal digits up to 9, but then there are the letters A, B, C, D, E and F in place of the decimal numbers 10 to 15:
Hexadecimal: 0 1 2 3 4 5 6 7 8 9 A B C D E F
Decimal: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
So a single Hexadecimal digit can show 16 different values instead of the normal 10.