what is the purpose of "bas" here? why not just "là"?
Not 100% sure, but it's my impression that adding the "bas" makes the location less specific. As in, "the dog walks over there somewhere in the direction I'm pointing" as opposed to "there is a doghouse in our yard, the dog walks there"
Why is "The dog walks over there?" incorrect?
DE là-bas = FROM over there. "The dog walks over there" would just be "Le chien marche là-bas"