Pending invites are people you have invited who have not yet accepted.
View pending invites
On the Members page, a Pending Invites section lists each invited email along with the role and an expiry date.

Expiry
Invitations expire after a set period. Once an invite has passed its expiry, it shows as Expired and the person will need a fresh invitation.
Cancel an invite
Select Cancel next to a pending invite to revoke it before it is accepted.
Next steps
Need to invite someone again? See inviting and removing members.