WPS (Wage Protection System)
The federal system through which wages are paid electronically so that payment is recorded and verifiable.
WPS exists so that wages are provably paid, on time and in full, rather than resting on either side's word. Payment runs through the banking system and leaves a record the ministry can see.
Requirements and coverage have expanded over time and differ by category of worker, so what applies to your arrangement is worth confirming rather than assuming.
Why it matters
Paying through the proper channel protects you as much as her. Cash with no record is the weakest possible position if a wage is ever disputed.
See also
This is general information, not legal advice, and the rules change. Confirm anything you intend to act on with a licensed Tadbeer centre or with MOHRE.