PAFL Follow Mix (On)

Pag 94 of the User guide has:

PAFL Follow Mix (On) = When PAFL is active on the master/mix channel strip, the channel being routed to PAFL will follow mix selection.


What does
the channel being routed to PAFL will follow mix selection
mean please?
Thank you

It means:
If you press the PAFL in the Master/Mix channel strip (far right), it will now follow all 16+1 mix buttons.
This way, you can, for example, quickly listen through all your monitor mixes one after the other without having to press PAFL again each time.