Since no one answered you Trevor I will.

The bore oil sprayers are (usually) mounted in an oil gallery which runs from the end of the engine to the other.

They are at the bottom and spray oil upwards to the piston and bore.

It helps cool the piston and helps keep things lubed.

Its good because you can run more power while keeping the piston temp to a sensible temp and it prevents the piston picking up in a bore and making a horrible mess.

A lot of engines have them as standard, a lot of diesels use them and a fair few petrol engines.

You use more oil but you have a better (read reliable) engine
with them.