Ninapomaliza kazi, ninapumzika sebuleni.

Ninapomaliza is one long verb made from several small pieces:

• ni- = I (subject marker for 1st person singular)
• -na- = present tense / present habitual (roughly “do / am doing”)
• -po- = “when / where” (a relative marker for a specific time or place)
• maliza = finish (verb root)

So ni-na-po-maliza → ninapomaliza = “when I finish / when I am finishing”.
Swahili just writes it as one word; you don’t put spaces between these parts.

In this sentence, -po- is talking about time, not place.

• As a relative marker, -po- basically means “when” or “at the time that”.
• The meaning is: “At the moment that I finish work, I rest in the living room.”

The same -po- can also be used for a place:

• Hapo ninapofanya kazi, kuna kelele nyingi.
  There where I work, there is a lot of noise.

So -po- covers both “when” (specific time) and “where” (specific place); here it’s clearly “when”.

Yes, you can say:

• Nikimaliza kazi, ninapumzika sebuleni.

The difference is a nuance:

• -po- (as in ninapomaliza)

  • Often used for a specific time: when I finish (at that time).
  • Feels a bit more neutral/straightforward “when”.

• -ki- (as in nikimaliza)

  • Often has a more conditional / whenever feeling:
    
    • If/whenever I finish work, I rest in the living room.

In everyday speech, for repeated actions like this, ninapomaliza kazi… and nikimaliza kazi… will usually both be understood as:

• “When(ever) I finish work, I rest in the living room.”

If you want to be very precise in formal grammar:

• -po- = definite “when”
• -ki- = “if / when(ever)” (conditional or repeated).

In Swahili, every finite verb normally needs its own subject marker.

So we get:

• ni-na-po-maliza = when *I finish*
• ni-na-pumzika = I rest

Even though English only says “I” once:

• When I finish work, Ø rest in the living room (no second “I”)

Swahili cannot drop the subject marker on the second verb.
You must say ninapumzika, not just napumzika.

So the structure is:

• Ninapomaliza kazi, ninapumzika sebuleni.
  When I finish work, I rest in the living room.

With -na- and -po- together like this, it most naturally describes a habitual or regular action:

• “When(ever) I finish work, I (normally) rest in the living room.”

It can also be understood as describing a general present rule about what happens when you finish work.

If you wanted to emphasise what is happening right now, you’d normally use extra context, e.g.:

• Siku hizi ninapomaliza kazi, ninapumzika sebuleni.
  These days when I finish work, I rest in the living room.

Or be more explicit with time expressions (today, nowadays, etc.).

You change the second verb to the future tense:

• Ninapomaliza kazi, nitapumzika sebuleni.
  When I finish work, I will rest in the living room.

Breakdown of the second verb:

• ni- = I
• -ta- = future
• pumzika = rest

You can also use another common pattern for a future time clause:

• Nitakapomaliza kazi, nitapumzika sebuleni.
  (When I have finished work, I will rest in the living room.)

Here nitakapomaliza = ni-ta-ka-po-maliza (“when I will have finished” / “when I finish” in the future).

Sebule = living room.
When you add -ni to many nouns in Swahili, it makes a locative (“in/at/on [that place]”).

So:

• sebule → sebuleni = in the living room
• shule → shuleni = at school
• nyumba → nyumbani = at home
• kazi → kazini = at work

In this sentence:

• Ninapumzika sebuleni. = I rest in the living room.

There is no separate word for “in”; the -ni on sebule does that job.

Swahili does not have separate words for “a” or “the” like English.
Context decides whether kazi means “work”, “a job”, or “the job/work”.

To say “my work”, you add a possessive:

• kazi yangu = my work
• Ninapomaliza kazi yangu, ninapumzika sebuleni.
  When I finish my work, I rest in the living room.

In the original sentence, kazi by itself can be understood as “work” or “my work” depending on context.

Yes, you can put the main clause first:

• Ninapumzika sebuleni ninapomaliza kazi.

It still means:

• I rest in the living room when I finish work.

In writing, many people will put a comma to show the pause:

• Ninapumzika sebuleni, ninapomaliza kazi.

Both orders are normal in Swahili:

• Ninapomaliza kazi, ninapumzika sebuleni.
• Ninapumzika sebuleni, ninapomaliza kazi.

The meaning stays the same; only the emphasis slightly changes (what you mention first).

Yes, that’s another correct way to express almost the same idea:

• Baada ya kumaliza kazi, ninapumzika sebuleni.
  After finishing work, I rest in the living room.

Differences:

• Ninapomaliza kazi…

  • Uses the relative marker -po- inside the verb.
  • Literally: When I finish work…

• Baada ya kumaliza kazi…

  • Uses the preposition baada ya = after.
  • Literally: After finishing work…

In everyday conversation, they are very close in meaning; both describe what you do once you have finished work.
The -po- form is a bit more compact and very common in spoken Swahili.