POS Menu is the point-of-sale ordering module used on POS devices in the admin checkout (walk-in sales rung up by staff). The Order: POS Menu tab has just two rows: PosMenu: Title (default POS Menu), used as the section heading for POS Menu items on admin order views, and Which categories are displayed on POS Menu (Meal Categories or Primary Categories), which decides whether the POS screen's category side menu and filters use your meal categories or the dedicated POS categories. Note that on the customer-facing order page the POS Menu section currently reuses the Grab And Go title instead of PosMenu: Title - a quirk in the current version, not something you can change.