First, you need to log in to your Plesk control panel. Refer below link

https://www.srilankahosting.lk/knowledgebase/getting-started-with-plesk/

The parameters located in the “DNS tab” of the “Service Plans > select a plan” section define how the DNS service on the Plesk-managed server will serve the DNS zones for websites hosted on that plan.

Master

A primary or master name server stores the zone file it serves locally, whereas a secondary server only retrieves a copy of this file from the primary.

Slave

A secondary or slave server retrieves a copy of the zone file from the primary name server.