The Sprwt Service Fee is a small fee added to certain orders. With the default settings: no fee on carts of $3.50 or less; 15% of the subtotal on carts from $3.50 up to $10; and above $10 a flat fee - $1.50 on a normal order, $1.75 on a POS order, or $1.50 on a proposal - plus any per-sale variable amount Sprwt has configured. Your account's exact values may differ; they live in the Payment group as Sprwt Service Fee (Amount $), (Min Amount on Cart to Apply), (Max Amount on Cart to Percentage Fee), (Percentage Fee), (Modules) (which order types it applies to) and (Apply) (subtotal, tips, delivery, bags). The fee also only applies at all when Sprwt has the Client Pays Fee setting turned on for your account (it is on by default) and the order type is one of the enabled modules.

Who pays it is your choice: Settings > Configuration > Business > Cart tab > Sprwt Service Fee Charged to - Customer (added to the cart total as a service fee) or Kitchen (not added to the customer's total - you absorb it). The Cart Service Fee setting on the same tab is a separate, optional fee you configure and keep yourself, independent of the Sprwt Service Fee.