Interpreting Cassandra replication json string

Author: Arya

When I run the following command in cqlsh

SELECT * FROM system_schema.keyspaces;

I get a list of keyspaces and for the replication column there is a json string that looks like the one below

 {'QQQ': '3', 'AAA': '3', 'class': 'org.apache.cassandra.locator.NetworkTopologyStrategy'}

What are the number 3's in the string above? are they related to write level and read level?

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