Where is the best place I could learn about what FRAME is?

agm.eth explained it well: 
“What we have in Frames is a new Web 3 primitive that Web 2 could never really power: an easy way to run app X while a user is still inside app Y, with little coordination between X and Y.

The interoperable identity and transaction record of the blockchain, along with the seamless handling of money and digital ownership, makes it possible to have a real and universal graph of user actions across consumer apps, something even Facebook at the height of its popularity couldn’t manage.”