What is starwars battlefront 3 about

Currently, it is about nothing as it doesn't exist. There has been no release and while Lucasarts has not denied that there will be a SWBF3, neither have they confirmed it.

Some people refer to SWBF: Elite Squad (I think) as version 3 but technically it is only a PSP version, nothing more.

If the game were to exist, it would be a strategy style Star Wars Game where you take control of various Star Wars characters/soldiers in a galactic battle across iconic Star Wars Locations.

Some suspect it will be an online title but without any official word, it is all just speculation.