The -sson patronymics
Scandinavian surnames are overwhelmingly patronymic: the ending -sson (Swedish), -sen (Danish/Norwegian) means “son of.” Andersson is “son of Anders,” Hansen “son of Hans.” A handful of these — Andersson, Johansson, Karlsson — cover a large share of Swedes.
Ornamental nature names
A distinctive second group are ornamental names, often coined in the 1800s by combining pretty nature words: Lindberg (“linden mountain”), Bergström (“mountain stream”), Lindgren (“linden branch”).