Teams are basically a way to be in contact with others that have the same or similar interests. It can be a great support system to be a part of a team that you share some similar interests or goals with others. It is helpful if you are in a team that you are active and post in them, but not a requirement. A "huddle" is a part of a team where you can post a quick note to the team that will scroll across that page for that day that you post it.
Hope this helps!