125 is short for a 125cc (the engine size for a) moped/
scooters. Mopeds such as this are available to under a basic licence called CBT (
Compulsory Basic Training) which are given to people learning how to drive. These licences can be given to 17 year olds. In the UK, mopeds/scooters are often used by gangs for drug deliveries or a form of a drive by attack/knife attack.