Shed Light On and A Bit

Shed Light On

To shed light on or shed some light on something is to give some new information about it, usually information that was unknown but important or that clears up a misunderstanding about it.
Ex: Sarah talked to Tom's mother yesterday and she shed some light on why Tom hadn't been to school this week. Apparently he's been quite sick with the flu but she hopes it'll clear up by weekend.
Ex: Lewis' new book sheds new light on the history of immigration and it's a very interesting read. I didn't realise people had been moving around so much for so many years.
Other verbs that can be used in the phrase shed some light on something are cast and throw. Throw usually implies that the information is more surprising.
Ex: The website threw some light on the punk subculture in our city. I had no idea there were so many bars where we could hear that kind of music in our own neighbourhood.
Ex: Scott asked if he could cast some light on the subject of cheap travel for us. He showed us how to find discount plane tickets and cheap hostels so we could take a much cheaper trip next time.

A Bit

When someone asks for a bit of something, they are asking for a very small amount of that thing. Usually, a bit is an amount small enough to hold in your hand.
Ex: Caroline loved making her mum's chilli recipe, but she liked to use a bit of chilli seasoning to make it a bit spicier than usual.
Ex: Josh always likes to be prepared when he travels. He carries his wallet, camera, and a bit of suntan lotion with him wherever he goes.
Just like a bit refers to a small amount of something, when you do something bit by bit, you complete the task slowly, one part at a time.
Ex: Some people like to paint their house all at once. But Callie prefers to do it bit by bit, one room at a time.
Ex: Bit by bit, Millie lost all of her money at the poker table. She was never a good gambler and kept making bad decisions on bets until all of her money was gone.