During the Battle of Britain, there were people who were not from Britain who helped the Royal Air Force (RAF) fight against the Germans. These people came from other countries to fight for Britain because they believed it was the right thing to do. They were called "non-British personnel" because they were not originally from Britain.
The people who came to fight for Britain were important because they had different skills and experiences than the British pilots. Some of them were already experienced pilots from their own countries and others were mechanics or ground crew who worked to make sure the planes were ready to fly. They worked together with the British pilots to protect Britain from the German planes.
There were people from lots of different countries who helped the RAF during the Battle of Britain, including Australia, Canada, Czechoslovakia, France, New Zealand, Poland, Belgium, South Africa and many others. They all came together to help Britain because they believed in freedom and wanted to stop the Germans from taking over Britain.
So, even though they weren't originally from Britain, these brave people played an important role in helping the RAF win the Battle of Britain. They showed that people from all over the world can work together to protect what is important.