The literal translation is: "слева" = "from left", "налево"="to left". When speaking about motion, the translation is like that. But when describing immobile objects both can mean the same. It is a problem of speaker's imagination.

One can say: "cлева от меня было дерево" or "налево от меня было дерево". Both mean: "there was a tree on the left of me".

But I think in this sense "слева" is used more often.