This is SAP Proprietary language to ensure that the SAP Components are Database independent. Each instance is installed with DB Client software to communicate with Database in Native Language.
The SAP Kernel which is O/S and DB Specific helps in the interpretation.
The user request is processed and it handovers (handshake) the task to Database process.
DBWP (Database work process) process and responds back to the R/3 work process. R/3 work process checks for frequently accessed content and keeps the copy in R/3 Buffer areas. (Frequently accessed data). The response rolls out into the user context before it is sent to the user.