Understanding pg wantedgeneration and pg currentgeneration

Hello,

Could you help me clarify what the difference of this attributes and how I can understand cluster health with this information?
Can I understand with this information synchronisation of my standby nodes?

For example my cluster status output:
UID HEALTHY PG LISTENADDRESS PG HEALTHY PG WANTEDGENERATION PG CURRENTGENERATION
keeper0 true 172.28.65.21:5432 true 2 2
keeper1 true 172.28.64.201:5432 true 4 4
keeper2 true 172.28.66.42:5432 true 2 2