Hexadecimal is a base16 way of representing numerical values in a way a human can remember, it is not easier for the computer to read it but it is for a human. Hex can have both letters and numbers, as soon as the binary value gets above 9 it is replaced with a letter. Numbers are used from 0 to 9 and letters are used between binary values 10 and 16, hex does not go above 16 instead it just simply gets another digit.
For example, if there is a hex code of D9 then in decimal, it represents the number 139.
Hope this helps!