Learn Hardcore Swahili: Ukisimama kwenye mteremko huu, utahisi upepo mkali usoni. - If you stand on this slope, you will feel a strong wind on your face.

u-: the subject prefix for you (singular)
-ki-: the conditional (or present-tense “when/if”) marker
simama: the verb root “stand”
Putting them together gives u-ki-simama: “if/when you stand.”

Why is utahisi in the future tense, and what is its structure?

Utahisi means “you will feel.” It has three elements:

Why use kwenye mteremko huu instead of katika mteremko huu?

Both kwenye and katika can mean “in” or “on,” but:

kwenye is more idiomatic for “on” or “at” a surface or slope
katika usually means “inside” or “within” an enclosed space
Since a slope is treated like a surface you stand on, learners typically choose kwenye: “on this slope.”

How does the adjective mkali agree with the noun upepo?

Swahili adjectives agree with their nouns by taking the same noun-class prefix. Here:

upepo (“wind”) belongs to noun class 11/14 with prefix u-
The adjective root is kali (“strong,” “harsh”)
To agree, kali takes the class-11 prefix m-, yielding mkali
Thus upepo mkali = “a strong wind.”

What does the locative suffix -ni do in usoni?

The suffix -ni marks the locative case, roughly “at/on/in.”

uso = “face”
usoni = “on the face” or “at the face.”
So utahisi upepo mkali usoni = “you will feel a strong wind on your face.”

Why is there a comma after huu, and is it necessary?

The comma separates the if-clause (Ukisimama kwenye mteremko huu) from the main clause (utahisi upepo mkali usoni).

In Swahili it’s optional but helps clarity, just like in English.
You can write it without the comma and still be correct:
Ukisimama kwenye mteremko huu utahisi upepo mkali usoni.