Can someone explain S2E7 Lonely Souls(SPOILER)

Im watching the show for the first time and ive heard a lot svout this episode but I jst wanna know if what i got from the last like 7 mins is right without spoilers.

So basically Leland killed Laura while possesed as Bob bcs The Giant says its happening again, lowkey idk what the white horse has to do with any of this😭