Who you referring to? British plates?

They take this format

A123 BCD. The "A" denotes the age of the vehicle. For example, G=1990/1991 H=1991/1992 J=1992/1993 and so on

The rest is a random sequence of 3 (sometimes 2) numbers, and 3 letters

You can also buy "personalised" plates, which can be things like your initials. For example, mine is W2 CJK (W is the age=2000, 2 is just 2, and CJK is my initials). That cost £700 by the way

You could have things like CHR 1S, or PEN 1S ( ) or A1 DAN or whatever

They're changing the system anyways, soon it will be regional based.