Wanafunzi wawili wanakula samaki sokoni.

Swahili verbs agree with their subject’s noun class by using a subject-prefix. In wanakula, we have: • Subject-prefix wa- for class 2 (because of wanafunzi)
• Tense/aspect marker -na- for present
• Verb root kula (‘eat’)
Putting them together gives wa + -na- + kula = wanakula, meaning they eat or they are eating.

The infix -na- marks the present tense (which can cover both habitual and progressive aspects). So wanakula can mean either: • They eat (habitually)
• They are eating (right now)
Context (and sometimes a time-word) tells you which sense is intended.

To change to the simple past, replace -na- with the past marker -li-. The subject-prefix wa- stays the same. So wanakula → walikula. The full sentence becomes:
wanafunzi wawili walikula samaki sokoni
(‘two students ate fish at the market’).

You follow the same pattern as with other nouns: • Two fish: samaki wawili
• Some fish: samaki kadhaa or samaki mengi
Numbers 2–5 and quantifiers like kadhaa (‘a few’) and mengi (‘many’) follow the noun.

Swahili often expresses location by adding the locative suffix -ni directly to a noun.
• soko (‘market’) + -ni → sokoni (‘at/in/​on the market’)
You don’t need a separate preposition. Alternatively, you can use katika soko to mean “inside the market,” but sokoni is more idiomatic for “at the market.”

You can either use the question-word je at the start or rely on rising intonation:
• Je wanafunzi wawili wanakula samaki sokoni?
• Wanafunzi wawili wanakula samaki sokoni?
Both mean Are two students eating fish at the market?