The two numbers in the middle of the registration state the year:
The first number will be a 1/5/6.
If it is a 1, it is registered between March and September: If it is a 5/6, the vehicle is registered after September and before March.
The second number states the year:
For example KC63 KFF was registered between Sept 2013 and March 2014.
Prefix Registration System
Vehicles registered pre 2001 are subject to a prefix and suffix system. The most common is prefix. The first letter represents the year the car was registered.
For example, M673 SWP was registered in 1994.
To find which year your car was registered, enter your registration into the DVLA vehicle check