Si estudio más, aprobaré el examen.

Because they are two different words:

• si = if
• sí = yes or an emphatic self/itself

So in Si estudio más, aprobaré el examen, si introduces a condition: if I study more.

After si for a real or possible future condition in Spanish, you normally use the present tense, not the future.

So Spanish says:

• Si estudio más, aprobaré el examen.

Not:

• Si estudiaré más... ❌

This is a very common pattern:

• Si tengo tiempo, iré.
• Si vienes, cenamos.

Even though the meaning refers to the future, the verb after si stays in the present.

Because it expresses the result of the condition: I will pass the exam.

The structure here is:

• Si + present, future

So:

• Si estudio más = the condition
• aprobaré el examen = the future result

This is one of the most basic conditional patterns in Spanish.

Yes, in some contexts, but it changes the feel slightly.

• Si estudio más, aprobaré el examen = If I study more, I will pass the exam
  This clearly points to a future result.

• Si estudio más, apruebo el examen = literally If I study more, I pass the exam
  In Spanish, the present can sometimes be used for a future idea, especially in informal speech, but aprobaré is the clearer and more standard choice here.

So for a learner, Si estudio más, aprobaré el examen is the safest model.

Because Spanish often drops subject pronouns when the verb already makes the subject clear.

• estudio already means I study
• aprobaré already means I will pass

So yo is not necessary.

You could say:

• Si yo estudio más, aprobaré el examen

but that usually adds emphasis or contrast, for example:

• Si yo estudio más, aprobaré el examen, pero él no.

más means more.

It has an accent mark to distinguish it from mas, which is a more literary word meaning but.

So:

• más = more
• mas = but

In modern everyday Spanish, mas is much less common, but the accent still matters.

The accent mark shows the stress and is required by Spanish spelling rules.

• aprobaré is the future tense of aprobar
• The ending -é marks I will

Compare:

• aprobaré = I will pass
• aprobare = not the normal form you want here

So the accent is an important part of the correct written form.

Yes, it is standard to use a comma when the si clause comes first.

So:

• Si estudio más, aprobaré el examen. ✅

If you reverse the order, the comma is usually not used:

• Aprobaré el examen si estudio más. ✅

This is similar to English, where an initial if clause is also often followed by a comma.

Yes. You can say:

• Aprobaré el examen si estudio más.

This means the same thing. The difference is mostly one of emphasis or style:

• Si estudio más, aprobaré el examen.
  Emphasises the condition first.

• Aprobaré el examen si estudio más.
  Starts with the result.

Both are completely natural.

This is a real or possible future condition.

It talks about something that could really happen:

• if I study more → I will pass

In Spanish, this pattern is:

• si + present, future

Compare it with a more hypothetical pattern:

• Si estudiara más, aprobaría el examen.
  If I studied more, I would pass the exam.

That second version sounds more hypothetical or less certain.

In Spanish, aprobar un examen is the normal way to say to pass an exam.

So:

• aprobar un examen = pass an exam
• suspender un examen = fail an exam

A direct translation using English logic can be misleading here. While pasar means to pass in many contexts, for exams the usual verb is aprobar.

A simple pronunciation guide is:

Si estudio más, aprobaré el examen
see es-TOO-dyo mahs, ah-pro-bah-REH el ehk-SAH-men

A few points:

• si sounds like see
• estudio has the stress on -tu-
• más has a clear a sound, like mahss
• aprobaré is stressed on the last syllable: -ré
• examen is stressed on xa

In standard Spain pronunciation:

• c and z before e/i often sound like th in think, but there is no c/z in that position here, so that feature does not affect this sentence much.

Yes, but the meaning changes slightly.

• Si estudio más = If I study more
  This compares with the current amount of study.

• Si estudio mucho = If I study a lot
  This focuses on a large quantity, not necessarily more than before.

So both are correct, but más and mucho are not identical.