Lucasarts formerly known as Lucasfilm Games, the interactive media subsection of the broader Lucasfilms studio, was founded in 1982, and created some of the most iconic video games in existence, most of which, interestingly enough, had nothing to do with Star Wars. They were the folks behind games like The Secret of Monkey Island, Day of the Tentacle, Grim Fandango, and Gladius, which I contest to this day deserved a better shake than it ever got.
In any case, nowadays, the studio still exists, but merely as a shell of what it once was. It's stopped producing games and exists now exclusively as a publisher, which means it's functionally dead in the water.
That hasn't changed with the news that Lucasfilm Games is now coming back to life.
It's a weirdly simple story that's somehow still hard to explain. The long and the short of it is that Disney has decided that now, every single Star Wars games that comes out will have a "Lucasfilms Games" logo stamped on it somewhere. This, functionally, means nothing -- there is no Lucasfilms game studio, and EA is still producing every Star Wars game currently being made, so it's not like the actual people working on each game are changing. So all this really amounts to is that Star Wars games, from here on out, will have one more studio you'll have to push through when working through the opening loading screen to access the game itself.
As for why Disney is doing this, well... it's branding, obviously. They want to make sure the Lucasfilm brand is attached to everything and anything adjacent to Star Wars. It's possible this is because they have plans to loan out the IP to other, non-EA studios in the future? But that's hardly a guarantee. It's merely speculation of a possibility on my end.
Regardless, it is what it is.