In SAP HANA system architecture, Name server is used to maintain topology of SAP HANA system. It details complete information about system landscape- all hosts in distributed environment, active components and services running on each component in a distributed system environment.
You can check service start time, memory used, CPU used, Process Id, port number and other details for each service under each component in your environment.
When you navigate to System Administration → Landscape tab of your HANA system, all the information provided there- Services, Hosts, Redistribution and System Replication information is relevant to landscape information.
You can check the status of each service/host under Landscape and it is up and active, a green signal is indicated.