The sqlserver.databases_bulk_copy_throughput event in Extended Events captures bulk copy throughput, but Microsoft’s official documentation doesn’t always provide granular details on all attributes. For attribute descriptions, the best approach is to query sys.dm_xe_object_columns to check metadata.
For the count attribute, it typically represents the number of bytes processed, but to confirm, you can compare it against actual bulk insert operations and check whether it aligns with row count or data volume.
If you're running bulk inserts, you can enable this event along with sqlserver.bulk_insert_complete or sqlserver.bulk_load_table_lock, It can give better insights.