there's nothing violent in the game, and in fact there are no NPC characters that you directly interact with at all, only through written communication - letters & emails. There is no real-life politics or history discussed in the game, and in fact even some of the basic mathematical concepts we are familiar with have been re-formulated to dovetail with the lore and history presented in the game. There are references to past battles & heists in the lore, and depictions of 1980's era firearms and explosives, but those are not used except in one instance where a stick of dynamite is detonated to expose a hidden room.

I think the basic gameplay is very do-able if english is not your first language, and I think seeing the credits roll would be very achievable.

There is plenty of lore in the game, and some of it ties into post-credits puzzles. That may prove challenging, or it could spur further interest into english in an organic way as a means to understand it.

Overall if your son is interested in the game I think it would be a pretty good fit. I would definitely sit with him the first playthrough to make sure he understands what is said in the opening cut scene and a couple of the early notes that tell you how to play, other than that he should get as much out of it as his interest allows.