Quando estudo no computador, fico curvado.

In Portuguese, the subject pronoun is often omitted because the verb ending already shows who is doing the action.

• estudo = I study
• fico = I become / I get / I stay

So eu is not necessary here. You could say Quando eu estudo no computador, fico curvado, but in normal Portuguese, especially in simple sentences like this, leaving out eu is very common.

The sentence describes a habitual or general situation, not just one specific moment.

• Quando estudo... = When I study...
• fico curvado = I get hunched / I end up hunched over

In Portuguese, the present tense is often used for things that happen regularly or typically. So this sentence means something like:

• Whenever I study on the computer, I get hunched over.

It is not limited to what is happening right now.

Quando means when.

In this sentence, it introduces a time clause:

• Quando estudo no computador = When I study on the computer

Because the sentence is about a repeated situation, quando can be understood as whenever in natural English.

So the full sense is:

• Whenever I study on the computer, I get hunched over.

Fico comes from the verb ficar, which is a very common verb in Portuguese. Depending on context, it can mean:

• to stay
• to become
• to end up

Here, fico curvado means I become hunched over or I end up hunched over.

That is slightly different from estou curvado:

• estou curvado = I am hunched over (describing your state)
• fico curvado = I get hunched over / I become hunched over (showing a change or result)

So fico curvado is a good choice if the idea is that studying at the computer causes that posture.

Yes. Curvado is an adjective, and adjectives in Portuguese usually agree with the person they describe.

If the speaker is male:

• fico curvado

If the speaker is female:

• fico curvada

That is because the adjective matches the gender of the speaker.

Curvado literally means bent or curved, but in this context it usually means something like:

• hunched
• bent over
• stooped

So fico curvado suggests bad posture while studying at the computer.

Depending on context, Portuguese might also use other expressions for posture, but curvado is perfectly understandable here.

No is a contraction of:

• em + o = no

So:

• no computador literally means in/on the computer

In practice, it refers to using the computer as the place or medium of study.

A learner should know, though, that in European Portuguese, people very often say ao computador when they mean at the computer.

So:

• estudo no computador = understandable, and can suggest studying using the computer
• estudo ao computador = often more natural in Portugal for I study at the computer

Both are useful to know, but ao computador is especially worth remembering for Portugal.

Yes, it is understandable and basically fine. However, in Portugal, many speakers would probably say:

• Quando estudo ao computador, fico curvado.

That is because ao computador is very common in European Portuguese for at the computer.

So the original sentence is grammatical and clear, but if you want a more typically Portugal-sounding version, ao computador is a strong alternative.

The comma separates the introductory time clause from the main clause:

• Quando estudo no computador, = subordinate clause
• fico curvado. = main clause

This is standard punctuation in Portuguese and also very natural in English:

• When I study on the computer, I get hunched over.

You may sometimes see short sentences without a comma in informal writing, but using the comma here is correct and recommended.

Yes, but the meaning changes a little.

• Quando estudo no computador, fico curvado
  = When I study on the computer, I get hunched over

• Quando estou no computador, fico curvado
  = When I am on the computer, I get hunched over

The first one is specifically about studying.
The second is broader and could include anything you do on the computer, such as working, browsing, or gaming.

So both are possible, but they are not exactly the same.

They are both in the 1st person singular present tense.

From estudar:

• eu estudo = I study

From ficar:

• eu fico = I become / I stay / I get

So the structure is:

• Quando
  • [I study]
• [I get]
  • curvado

This is a very useful pattern in Portuguese for talking about repeated results:

• Quando leio muito, fico cansado.
  = When I read a lot, I get tired.

• Quando trabalho demais, fico stressado.
  = When I work too much, I get stressed.