Teman perempuan saya memasak jamur di apartemennya setelah pulang kerja.

In Indonesian, the possessor usually comes after the noun.

• teman perempuan saya = my female friend
• rumah saya = my house
• guru saya = my teacher

So saya means my here because it follows a noun phrase. The same word saya can also mean I when it is the subject of a sentence.

Usually, no. Teman perempuan normally means a female friend.

If you want to clearly say girlfriend in the romantic sense, Indonesian usually uses pacar saya. So a learner should not automatically read teman perempuan saya as romantic.

Both perempuan and wanita can refer to a female/woman, but they have slightly different feel.

• perempuan: very common, neutral, straightforward
• wanita: often sounds a bit more formal or polished

In teman perempuan, perempuan simply tells you the friend is female.

Masak is the root. Adding meN- gives the active verb memasak, which is the standard form for to cook something.

• masak can be a root, and in casual speech people may say it as a verb
• memasak is the fuller, more standard form

So memasak jamur is a normal way to say cook mushrooms.

It marks an active verb, especially when the verb has an object.

Here:

• memasak = to cook
• jamur = the thing being cooked

So the structure is a normal active sentence:
Teman perempuan saya + memasak + jamur

The prefix changes shape depending on the first sound of the root. With masak, it becomes memasak.

Indonesian normally does not use articles like English does.

So jamur can mean:

• a mushroom
• the mushroom
• mushrooms
• the mushrooms

The exact meaning depends on context. Indonesian often leaves that kind of information unstated unless it matters.

It could be either. Indonesian nouns often do not show number unless the speaker wants to make it explicit.

So jamur may mean:

• one mushroom
• some mushrooms
• mushrooms in general

If needed, Indonesian can make plural clearer in other ways, such as context, numbers, or reduplication like jamur-jamur, but that is not necessary here.

Because di marks a location, while ke marks movement toward a destination.

• di apartemennya = in/at her apartment
• ke apartemennya = to her apartment

Since the cooking happens there, di is the correct choice.

Here, -nya shows possession: his/her/their.

So:

• apartemen = apartment
• apartemennya = his/her apartment

In this sentence, it is understood as her apartment because the person mentioned is a female friend. But -nya itself does not mark gender.

Because -nya attaches directly to the noun.

• apartemen
  • -nya = apartemennya

The double n appears naturally because apartemen already ends in n, and then -nya is added.

Because Indonesian often omits a repeated subject when it is already obvious.

In this sentence, the understood subject of pulang kerja is the same person as the main subject, namely teman perempuan saya.

So setelah pulang kerja means:

• after returning home from work
• after she got home from work

If you want to make the subject explicit, you could say setelah dia pulang kerja.

Pulang means to go home / return home.
Kerja means work.

Together, pulang kerja is a common expression meaning:

• go home from work
• come home from work
• return from work

So setelah pulang kerja is a natural way to say after getting home from work.

Yes. Indonesian word order is fairly flexible with time phrases.

You can also say:

Setelah pulang kerja, teman perempuan saya memasak jamur di apartemennya.

That is also natural. Putting it first gives the time information more prominence.

You do not know from the verb form alone. Indonesian verbs do not change the way English verbs do for tense.

So memasak can fit different time frames depending on context:

• past
• present
• future

If the speaker wants to be clearer, they can add time words such as kemarin for past or besok for future.