Learn Hardcore Swahili: Ukisha pakua faili, nipe nenosiri lako ili niweze kulifunga salama. - Once you have downloaded the file, give me your password so that I can lock it safely.

u- (you, 2nd person singular subject)
-ki- (when/if)
-sha- (completive, “already”) followed by the verb. So Ukisha pakua ≈ “once you’ve already downloaded.”

Can I write Ukishapakua faili instead of Ukisha pakua faili?

Yes. Both are common:

Ukishapakua faili = u-ki-sha-pakua (all fused)
Ukisha pakua faili = u-ki-sha [aux], then the main verb You’ll also see Ukiisha kupakua faili, which uses the full verb -isha “to finish” with an infinitive. All three mean “once you have downloaded the file,” with tiny stylistic differences only.

I thought pakua means “dish up/serve” food. Why is it used for “download”?

Modern IT usage extended pakua to mean “download,” while pakia means “upload.” You may also hear shusha (to bring down) for “download,” especially informally. Context usually disambiguates “dish up” vs “download.”

What is nipe exactly? How is that imperative formed with pronouns?

The verb is -pa “to give.” The affirmative singular imperative is the bare stem, and object markers go before it:

nipe = ni- (me) + pe (imperative stem) = “give me”
Plural: nipeni = “you all, give me”
Negative singular: usinipe = “don’t give me”
Negative plural: msinipe = “you all, don’t give me”

Is nipe polite enough? How could I sound more polite?

On its own it’s fairly direct. To soften it:

Tafadhali nipe nenosiri lako.
Naomba nenosiri lako.
Naweza kupata nenosiri lako? (more indirect)

Why is it nenosiri and not neno la siri?

Nenosiri is the standard, lexicalized compound for “password.” Neno la siri literally means “a secret word”; people will understand it, but nenosiri (often one word) is the usual tech term. You may also hear nywila in some regions.

Why is it nenosiri lako and not nenosiri yako?

Possessives agree with the noun class. Nenosiri is a class 5 noun (its plural is class 6: manenosiri is rare, but the class behavior is like class 5/6 nouns such as gari/magari). Class 5 uses la- for possession:

langu, lako, lake, letu, lenu, lao Hence nenosiri lako = “your password.” (Compare: jina lako, gari lako.)

What does ili niweze add? Could I just say ili nilifunge salama?

ili introduces purpose, and the verb that follows normally takes the subjunctive.
niweze = “that I may be able to.” So ili niweze kulifunga = “so that I can (am able to) lock it.”
You can say ili nilifunge salama (“so that I lock it safely”), which is fine and a bit more direct. Using weza adds the nuance of ability/permission.

In kulifunga, why is there li and where does it go?

ku-li-funga = infinitive marker ku- + class-5 object marker li- + verb stem funga.
In infinitives, the object marker comes right after ku-:

kuliangalia = “to look at it” (class 5 object)
kuviweka = “to put them” (class 8 object)

Why specifically li-? What noun class is faili?

In standard usage, faili (file) patterns as class 5, with the plural mafaili (class 6). The class-5 singular object marker is li-, hence kulifunga.
Some speakers treat certain borrowings as class 9; if you hear kuifunga faili, that reflects class 9 usage, but class 5 (li-) is the recommended/most common for faili in IT contexts.

Could I say kufunga faili without an object marker? Or kuifunga?

kufunga faili (no object marker) is perfectly fine; the explicit noun is the object.
kulifunga uses a pronoun-like object marker (“lock it”), which is common when the object is already known or previously mentioned.
kuifunga uses the class-9 marker i-; that’s only appropriate if you’re treating faili as class 9. Stick with li- in standard IT Swahili for faili.

Does kufunga here mean “close the file” or “lock/protect it”? Is salama the best way to say “safely”?

Funga can mean “close,” “lock,” “shut,” “fasten,” even “fast (not eat).” In computing it can be ambiguous. If you mean security, you can be clearer:

kulilinda salama = protect it safely
kuliweka salama = put it in a safe state
kulifunga kwa nenosiri = lock it with a password Salama works well adverbially (“safely”). You’ll also see kwa usalama (“for safety/security”), e.g., kulifunga kwa usalama.

Is the word order flexible? Can I put the Ukisha... clause at the end?

Yes. Both orders are fine:

Ukisha pakua faili, nipe nenosiri lako...
Nipe nenosiri lako ukisha pakua faili.

How else can I say “once/as soon as/after you download”?

“Once/as soon as”: Mara tu ukishapakua faili, ...
“After”: Baada ya kupakua faili, ...
“When you have (downloaded)”: Utakaposhapakua faili, ... (slightly more formal)

How would this change for plural “you” (you all)?

Mkisha pakua faili, nipeni nenosiri lenu ili niweze kulifunga salama. Changes:
m- (2nd person plural) in mkisha
nipeni (imperative plural)
lenu (your, plural possessive for class 5)

Is kisha also a word meaning “then”? How is that different from Ukisha here?

Yes. kisha by itself means “then/after that,” e.g., Pakua faili, kisha ufunge.
In Ukisha, the -ki- “when” + -sha- “already” are glued to the subject marker: it means “when/once you have ...,” not just “then.”