Which about "least 3 regions"？？

[startjava]

Multi-cluster Pulsar instance​

When you deploy a global Pulsar instance, with clusters distributed across different geographical regions, the configuration store serves as a highly available and strongly consistent metadata store that can tolerate failures and partitions spanning whole regions.

The key here is to make sure the ZK quorum members are spread across at least 3 regions, and other regions run as observers

[startjava]

For example, assume a Pulsar instance with the following clusters us-west, us-east, us-central, eu-central, ap-south. Also assume, each cluster has its own local ZK servers named such as the following:

zk[1-3].${CLUSTER}.example.com

In this scenario, if you want to pick the quorum participants from a few clusters and let all the others be ZK observers. For example, to form a 7 servers quorum, you can pick 3 servers from us-west, 2 from us-central and 2 from us-east.

This method guarantees that writing to the configuration store is possible even if one of these regions is unreachable.

What mean top text？？？