Eu corto a banana às rodelas para o iogurte.

Yes, you can often leave out eu in Portuguese.

Portuguese verbs usually show who the subject is, so corto already means I cut. That means:

• Eu corto a banana... = more explicit, more emphatic, or clearer in context
• Corto a banana... = very natural in everyday Portuguese

You might keep eu if you want contrast, for example:

• Eu corto a banana, tu preparas o iogurte.

So in this sentence, eu is correct, but not always necessary.

Portuguese uses the definite article much more often than English.

So where English often says:

• I cut banana

Portuguese more naturally says:

• corto a banana

Here, a banana means the banana, but in many everyday cases it can also sound natural where English would just use banana more generally.

This is very common in Portuguese, especially with everyday objects and food.

Corto is the 1st person singular present form of the verb cortar, which means to cut.

So:

• cortar = to cut
• eu corto = I cut

Other present-tense forms are:

• tu cortas
• ele/ela/você corta
• nós cortamos
• vocês cortam
• eles/elas cortam

In this sentence, eu corto can mean:

• I cut (habitually / generally)
• sometimes I’m cutting, depending on context

But if you specifically want I am cutting right now, European Portuguese often prefers:

• Estou a cortar a banana...

Às rodelas means into slices / into rounds / in round slices.

A rodela is a round slice, like a slice of banana, carrot, sausage, cucumber, etc.

So:

• cortar às rodelas = to cut into round slices

This is a very common expression in Portuguese.

Examples:

• Corto a cenoura às rodelas.
• Corta o pepino às rodelas.

Because Portuguese often uses the pattern:

• cortar algo às rodelas
• cortar algo aos cubos
• cortar algo às fatias

Here às is a contraction of:

• a + as = às

This construction is idiomatic. It tells you the shape or style in which something is cut.

So:

• às rodelas = into round slices
• aos cubos = into cubes
• às tiras = into strips

You should learn às rodelas as a set expression.

Because the banana is being cut into multiple slices, not one.

So:

• rodela = one round slice
• rodelas = slices

That is why Portuguese says:

• corto a banana às rodelas

The idea is I cut the banana into slices.

Sometimes yes, but às rodelas is the more standard and idiomatic expression with cortar.

So for a learner, the safest version is:

• cortar às rodelas

You may also hear em rodelas in some contexts, especially when describing the final form of something, but with this verb pattern, às rodelas is the one you should remember first.

Para o iogurte means for the yogurt.

It shows purpose: the banana is being cut for use with the yogurt.

So the meaning is something like:

• I cut the banana into slices for the yogurt
• I slice the banana to put in the yogurt

It sounds like the banana is being prepared as part of the yogurt dish or snack.

Yes, but the meaning changes slightly.

• para o iogurte = for the yogurt, intended for it, to use with it
• no iogurte = in the yogurt, inside it

So:

• Corto a banana às rodelas para o iogurte = I slice the banana for the yogurt
• Corto a banana às rodelas no iogurte would sound less natural in this structure, because it suggests the cutting is happening in the yogurt

If you want to say I slice the banana to put it in the yogurt, a more natural sentence might be:

• Corto a banana às rodelas para pôr no iogurte.

Again, Portuguese uses definite articles more often than English.

So where English says:

• for yogurt

Portuguese often says:

• para o iogurte

This is very normal. The article does not always have to sound as specific as the in English.

By itself, eu corto is the present tense, and it usually suggests:

• a habitual action
• a general action
• something you do as a routine

So it often feels like:

• I cut / I slice the banana...

If you want to emphasize that it is happening right now, European Portuguese usually prefers:

• Estou a cortar a banana às rodelas para o iogurte.

That is the usual progressive form in Portugal.

The given word order is natural:

• Eu corto a banana às rodelas para o iogurte.

Portuguese word order is fairly flexible, but not all changes sound equally natural.

This version is good because it goes in a clear order:

1. subject: Eu
2. verb: corto
3. object: a banana
4. manner/result: às rodelas
5. purpose: para o iogurte

You could omit eu, but otherwise this order is a very good standard pattern for learners.

Yes, it is understandable and grammatically correct.

That said, in real everyday speech, a native speaker might also say something slightly more explicit, such as:

• Corto a banana às rodelas para pôr no iogurte.

That version makes the purpose clearer: the banana is being cut to put into the yogurt.

Still, your original sentence is perfectly good for learning and sounds natural enough.