The people of Skara Brae were farmers and fishermen.
They kept cattle and a few pigs. They also kept sheep or goats - it is impossible from bone remains to say which. They may have kept both. They grew crops, chiefly barley, but also some wheat.
We don't know a great deal about their fishing. Almost no fishing tackle has been found in the material recovered from the site. But a large amount of fishbone has been identified - mainly cod and saithe. This suggests most of their fishing was coastal.