Learn Hardcore Swahili: Katibu atakuwa ofisini alfajiri kesho. - The secretary will be at the office at dawn tomorrow.

Because katibu (“secretary”) is a single human subject. Third person singular for a human takes a-. For plural humans, you’d use wa- (e.g., “they will be” = watakuwa). For many inanimate nouns, you’d see i- (e.g., “it will be” = itakuwa).

What does the -ni in ofisini do?

The suffix -ni turns a place noun into a locative: “in/at the office.” So ofisi = “office,” ofisini = “in the office.”

Can I say katika ofisi or kwenye ofisi instead of ofisini?

Yes:

ofisini is the most natural, compact way.
katika ofisi is fine, a bit more formal.
kwenye ofisi is very common in everyday speech. All mean “in the office.”

Could I say kazini instead of ofisini?

Yes, but it changes the nuance:

ofisini = in the office (the physical office)
kazini = at work (not necessarily that specific office)

Why is there no word for “at” before alfajiri or kesho?

Time words like alfajiri (dawn) and kesho (tomorrow) act adverbially on their own—no preposition is needed. Swahili often just places such time expressions directly in the sentence.

Is the order alfajiri kesho fixed? Can I say kesho alfajiri?

Both are possible. You’ll hear:

… ofisini alfajiri kesho and
… ofisini kesho alfajiri. “Tomorrow at dawn” is often said as kesho alfajiri, but word order here is flexible and can be used for emphasis or rhythm.

What’s the difference between alfajiri and asubuhi?

alfajiri = dawn, the very early hours (roughly before/around sunrise).
asubuhi = morning (after sunrise through late morning). For “early morning,” you can also say asubuhi mapema.

Could I start the sentence with the time phrase?

Yes, for emphasis you can front time:

Kesho alfajiri, katibu atakuwa ofisini.

What’s another way to say “will be (present) in the office,” like emphasizing presence?

Use kuwepo (to be present):

Katibu atakuwepo ofisini… (He/She will be present at the office…) It slightly emphasizes actual presence/availability more than the neutral atakuwa ofisini.

How do I make it negative: “will not be in the office …”?

Use ha- + -ta- + verb:

Hatakuwa ofisini alfajiri kesho. With the “present” nuance: Hatakuwepo ofisini alfajiri kesho.

How do I say it in the plural: “The secretaries will be …”?

Plural of katibu is makatibu, and verb agreement switches to plural human wa-:

Makatibu watakuwa ofisini alfajiri kesho. Note: Although the plural form starts with ma-, humans take class 2 agreement (wa-) on verbs and adjectives.

Does katibu mean “the secretary” or “a secretary”? There’s no article.

Swahili has no articles. Katibu can be “the” or “a” depending on context. If you need to mark specificity, use demonstratives or other determiners (e.g., katibu yule = “that secretary,” katibu fulani = “a certain secretary”).

Can I drop the location and just say someone “will be” with no complement?

In practice, kuwa normally needs a complement (a place, state, or predicate). Atakuwa alone is typically incomplete unless the complement is understood from context.

How do I say “in his/her office” instead of just “in the office”?

Add a possessive with kwake:

Ofisini kwake = “in his/her office.” Example: Katibu atakuwa ofisini kwake…

How would I express the present equivalent “is in the office”?

Commonly with the -ko/-po/-mo locative forms:

Neutral/general: yuko ofisini
More emphatic/present: yupo ofisini
Inside nuance: yumo ofisini All mean “he/she is in the office,” with slight differences in emphasis/location type.

Any pronunciation tips for the words here?

katibu: ka-TI-bu (stress is penultimate in Swahili).
atakuwa: a-ta-KU-wa.
ofisini: o-fi-SI-ni.
alfajiri: al-fa-JI-ri (j as in “jam”).
kesho: KE-sho (sh as in “shoe”).