Why is there a red circle with feet inside above my sims head?

This means that your Sim can't get where you told him to (or where he wants to). This is a game play issue: Perhaps you ordered him to go into a house where he has no permission to enter, or into a room where someone else is blocking the door, etc.

The most common cause of this for me is tight placement of objects from Buy mode. For instance, If you only have a small, narrow room and basically form a "hallway" of empty space in front of your couch before the TV/decorations, your Sims will have difficulty going down there if someone else is already on the couch.