Active-passive availability is one way to configure a distributed database to offer high availability.
In an Active-Passive Availability setup, all traffic is routed through a single active replica, and changes are copied to a backup passive replica. If the active replica fails, the passive one takes over. However, the active one might fail before the passive one copies all the data over, leading to data loss. Plus, it can take a while for the passive replica to boot up, causing some RTO.
Other configurations include active-active availability and multi-active availability.