I can't understand what active hours means in the basic plan pricing.

Hello Support,

In the licensing features I can see for the Basic plan which is $39/month has an active hour of 2000 hours. Can you explain in details what does the active hours mean? I didn't understand the description of the active hours.
I want to know if this number of hours is per user per month or an aggregation for all users per month. And also when the active hours are recorded and stop?