40 min time limit on 1:1 meeting with a pro licence

Hello,

I have a Pro license and I don't understand what this sentence means:

"1 host and 1 or more participants joined. Only one person remains in the meeting.
The meeting will end 40 minutes later if no one else joins"

Anyone can help please?

What does "only 1 person remains"?

And what if this person comes back to the meeting?

Thanks everyone!