You can find lots of details here - https://helpcenter.veeam.com/docs/backup/vsphere/storeonce_supported_features.html?ver=120

Is there anything specific you want to know?

In general there are two modes to access a StoreOnce Catalyst Store; Low and High Bandwidth mode.

The first one does source-side deduplication at the Veeam gateway server and might be able to increase performance if you have a slow connection to the StoreOnce. 

But if you have a fast connection, like 10GE or Fibrechannel, then the high bandwidth mode will be recommended. This will use target side deduplication and Veeam will transfer more data to the StoreOnce. At the end you will see the same deduplication rate, but performance increases.