i need help on why it was a turning point- i would like answers please just a couple of bullet points to start it off. i only need to write thre paragraphs so it should be easy i need why aswell[font="Impact"][/font]

You are right to stop and thin a little while before you answer this question.

Questions like these require you to understand what happened AFTER the Battle of Britain, as well as what happened during it.

There is an article which will help you here.
Your first two paragraphs, therefore, could be on: 1. Hitler's overwhelming success before the Battle of Britain, and 2. the setback the BoB gave him.

For the third, you could give some more results of the Battle of Britain, but what about suggesting that maybe it was NOT a great turning point. This alternative history site argues that Operation Sealion was going to fail anyway, and you have to ask yourself if merely stopping Hitler invading went anyway towards actually WINNING the war.
If you are looking for turning points of WWII, Hitler's invasion of Russia, or the battles of Stalingrad, Kursk and/or El Alamein, are much better candidates.