Translation:Are they cooking for me?
Wananipika? = Are they cooking me? [I am the food]
ia? = Are they cooking
for me? / Are they cooking me something?
verb conjugation (mnyambuliko wa vitenzi) . In this case the verb 'pika' is conjugated to the form of kutendea/kufanyia, i.e. doing an action for/on behalf of someone. So the suffix '-a' becomes '-ia/-ea', depending on the verb
Pika - pikia
Cheza - chezea
It will depend on the noun class of the object .e.g. onion (kitunguu, noun class 'Ki/Vi') as an indirect object would be: 'Wanani
As a direct object, it depends on whether you're speaking generally or referring to a specific onion ('a/an' versus 'the'):
Are they cooking an onion for me? - Wananipikia kitunguu?
Are they cooking the onion for me? - Wanani
you're welcome! The hardest part really is mastering noun classes. Once you're comfortable with those, you basically know Swahili