Teman saya optimis bahwa dia bisa mengelola proyek sampingan dan kuliah sekaligus.

In Indonesian, adjectives can function directly as predicates without a verb like “to be.”

• Teman saya optimis.
  Literally: Friend my optimistic. → “My friend is optimistic.”

You normally do not add adalah before an adjective in a simple sentence like this.

Use adalah mainly:

• Before nouns, not adjectives:
  
  • Dia adalah dokter. = He/She is a doctor.
• In more formal or written contexts for emphasis/clarity.

So:

• ✅ Teman saya optimis.
• ❌ Teman saya adalah optimis. (sounds unnatural)

Yes, you can, but the focus changes a bit.

• Teman saya optimis.
  Focus: my friend and their state. Statement about “my friend” now.
• Saya punya teman yang optimis. = “I have a friend who is optimistic.”
  Focus: the existence of such a friend; you’re introducing a kind of friend you have.

Both are grammatical, but:

• The original sentence talks about that specific friend.
• “Saya punya teman yang optimis” feels more like introducing a new friend into the conversation.

Both appear in Indonesian.

• optimis – very common in everyday speech and writing.
• optimistis – a bit more formal, closer to the original form from other languages.

In practice:

• Teman saya optimis…
• Teman saya optimistis…

Both are acceptable and mean “my friend is optimistic.” Most speakers use optimis in daily conversation.

bahwa works like “that” in English in clauses like “I think that… / I’m sure that…”.

In the sentence:

• Teman saya optimis bahwa dia bisa…
  = “My friend is optimistic that he/she can…”

You can often omit bahwa, especially in spoken Indonesian:

• Teman saya optimis dia bisa mengelola…
• Teman saya optimis bisa mengelola… (also natural; the subject is understood)

So:

• With bahwa → slightly more explicit, a bit more formal/clear.
• Without bahwa → very natural in speech.

dia is a third-person singular pronoun:

• It can mean he or she (Indonesian does not mark gender here).

In context:

• Teman saya optimis bahwa dia bisa…
  “My friend is optimistic that he/she can…”

About dropping it:

• In careful, clear sentences, keeping dia is good.
• In more casual speech, people might say:
  • Teman saya optimis bisa mengelola proyek sampingan dan kuliah sekaligus. The subject (dia / teman saya) is understood from context.

So dia is not always mandatory if the subject is obvious, but including it avoids ambiguity, especially in writing.

All three relate to ability, but with nuances:

• bisa – most common, neutral “can / be able to” (ability or possibility)
  
  • dia bisa mengelola… = he/she can manage…
• dapat – similar to bisa; often a bit more formal or written
  
  • dia dapat mengelola…
• mampu – emphasizes capability/competence, sounds stronger
  
  • dia mampu mengelola… = he/she is capable of managing…

In this sentence you could say:

• dia bisa mengelola… (natural, everyday)
• dia dapat mengelola… (slightly more formal)
• dia mampu mengelola… (stresses that the friend is really capable)

All are grammatical; bisa is the most neutral choice.

mengelola means “to manage / to run / to handle (a project, business, etc.)”

• Root: kelola (not usually used alone in everyday speech; it appears mostly inside forms like mengelola, pengelolaan)
• Pattern: meN- + kelola → mengelola

Examples:

• Dia mengelola sebuah usaha kecil. = He/She manages a small business.
• Saya harus mengelola waktu dengan baik. = I have to manage my time well.

So in the sentence, mengelola proyek sampingan = “manage a side project.”

Yes, sampingan functions like an adjective here.

• proyek = project
• sampingan = something extra / on the side / secondary

So proyek sampingan = “a side project” (not your main job or main study, but an extra project).

Position:

• Indonesian adjectives usually come after the noun:
  • proyek sampingan (project + side)
  • pekerjaan sampingan = side job
  • penghasilan sampingan = side income

kuliah can be both a noun and a verb, depending on context.

In this sentence:

• kuliah is best understood as a noun: “college / university studies / classes”.

So:

• mengelola proyek sampingan → manage a side project (verb phrase)
• dan kuliah → and (his/her) studies / college (noun)

Overall: manage a side project and college at the same time.

You also see kuliah as a verb:

• Saya kuliah di Jakarta. = I study at a university in Jakarta.

sekaligus means “at the same time / simultaneously / in one go.”

Position:

• It often appears after what it describes, especially at the end of the phrase or sentence.

In this sentence:

• mengelola proyek sampingan dan kuliah sekaligus
  = “manage a side project and college at the same time.”

Other examples:

• Dia bekerja sambil kuliah sekaligus.
• Bisa makan dan belajar sekaligus? = Can (you) eat and study at the same time?

You could also rephrase with:

• pada saat yang sama = at the same time
  But sekaligus is shorter and very natural here.

Indonesian does not usually mark tense with verb changes like English. Time is understood from context or from time words.

In:

• Teman saya optimis bahwa dia bisa mengelola…

It could mean:

• “My friend is optimistic that he/she can manage…” (general ability now or in the future).

If you want to make the future explicit, you can add akan:

• Teman saya optimis bahwa dia akan bisa mengelola proyek sampingan dan kuliah sekaligus.
  = “My friend is optimistic that he/she will be able to manage…”

But in normal conversation, context (e.g., talking about next semester) usually makes the time clear without extra markers.

Yes, that’s very natural, especially in spoken Indonesian.

Variations:

• Teman saya optimis bahwa dia bisa mengelola… (full, explicit)
• Teman saya optimis dia bisa mengelola… (no bahwa, still explicit subject)
• Teman saya optimis bisa mengelola… (subject understood from context)

The last one is common when:

• It’s obvious that “the one who can manage” is the friend.
• You’re speaking informally.

In careful or formal writing, including dia (and sometimes bahwa) can be clearer.

Indonesian does not change dia for gender:

• dia = he / she (gender-neutral)

So:

• Teman saya optimis bahwa dia bisa…
  could refer to a male or a female friend, depending on context.

If you really need to mark gender, people might:

• Add a noun: teman perempuan saya (my female friend), teman laki-laki saya (my male friend)
• Or use the person’s name instead of dia.

The sentence is in a neutral–slightly formal register:

• All words (teman, optimis, bahwa, dia, bisa, mengelola, proyek sampingan, kuliah, sekaligus) are standard Indonesian.
• It’s perfectly fine for:
  • Everyday conversation
  • Writing (emails, messages, essays)
  • Semi-formal contexts

In casual speech, you might simplify:

• Teman aku optimis bisa ngelola proyek sampingan sama kuliah sekaligus.
  (using aku, ngelola, sama – more colloquial/Jakarta style)

But the original sentence is fully natural and acceptable in most situations.