AWS Database Migration Service provides functionality to migrate data from source data stores (such as RDBMS) to destination data stores (such as RDBMS, or S3).

DMS Replication Instance - Provisioned compute which will be used to perform replication tasks. MDAA ensures these are private and encrypted.
DMS Endpoint - Source and target data sources from/to which data will migrated. MDAA ensures that endpoint credentials are securely managed exclusively through AWS Secrets Manager, or via AWS Role credentials.
DMS Replication Task - Tasks move data between DMS Endpoints, and are executed using Replication Instance compute.