When a clan is closed what does that mean?

There are 3 settings for a clan... Invite only, anyone can join and closed. What does closed mean

Invite only means people can still apply to the clan and wait for approval. Closed removes that option.

Anyone can join means they can join anytime without approval.
invite only means that they must wait for approval by an elder or leader.
closed means that only elder and leader can invite people to join.

inviting people is available in all three options, but only elder and leader can invite.