Needs Attention refers to a texting conversation that, well, needs attention. It means that a certain contact, or a certain conversation, still needs something to be done by a user in order for it to be considered completed.
Specifically, a Needs Attention conversation or thread occurs when:
The contact has responded (whether to an initial message or a subsequent reply from a user) and hasn't received a reply yet
The user has not yet filled a report for this contact via this Peer-to-Peer or Broadcast Texting action
If the user either sends a reply, or fills a report, the conversation/thread will no longer be a Needs Attention thread.
Needs Attention conversations are often the high-priority ones that admins want to reassign to themselves (or to other volunteers) at the end of a text bank, to make sure that contacts receive replies. Read more about texting reassignment here.