Eliminei a despesa supérflua, de modo que poupei mais.

Both are in the pretérito perfeito in Portuguese, which is usually the tense used for a completed action in the past.

• eliminei = I eliminated / I got rid of
• poupei = I saved

In this sentence, both actions are presented as completed:

• first, the speaker got rid of an unnecessary expense;
• as a result, the speaker saved more.

For an English speaker, this tense often matches the simple past.

Portuguese often leaves out the subject pronoun when it is clear from the verb ending.

• Eliminei already tells you the subject is I
• so eu is optional

This is very normal in Portuguese, including European Portuguese.
You could say Eu eliminei a despesa supérflua, but it usually sounds more emphatic, as if you want to stress I.

Portuguese often uses the definite article more than English does.

Here, a despesa supérflua means something like:

• the unnecessary expense
• or that unnecessary expense

The article makes the noun phrase sound more complete and natural. In many contexts, leaving out the article would sound less idiomatic.

Despesa means expense or expenditure. It is a noun.

Gasto can also refer to spending or an expense, but there is a slight difference in feel:

• despesa is often a bit more formal or accounting-like
• gasto is very common in everyday language and can feel more general

Examples:

• reduzir despesas = to reduce expenses
• os meus gastos mensais = my monthly spending / my monthly expenses

In this sentence, despesa fits well because the tone is slightly formal.

In Portuguese, adjectives often come after the noun, much more often than in English.

So:

• despesa supérflua = superfluous / unnecessary expense

This is the normal order here.

If an adjective comes before the noun in Portuguese, it can sometimes change the tone, emphasis, or even the meaning. For this sentence, despesa supérflua is the straightforward, natural order.

Because adjectives in Portuguese must agree with the noun in gender and number.

• despesa is feminine singular
• so the adjective must also be feminine singular: supérflua

Compare:

• o gasto supérfluo = the unnecessary expense/spending item
• a despesa supérflua = the unnecessary expense
• as despesas supérfluas = the unnecessary expenses

De modo que means so that, thus, or in such a way that, depending on context. In this sentence, it introduces a result:

• Eliminei a despesa supérflua, de modo que poupei mais.
• I eliminated the unnecessary expense, so I saved more.

Here it is basically expressing consequence: one action led to the other.

It sounds a little more formal or polished than simply saying:

• por isso
• por isso, poupei mais
• então poupei mais

Yes, it is correct and natural, but it sounds a bit more formal or written than some everyday alternatives.

Common alternatives include:

• por isso = that’s why / so
• assim = thus / so
• por isso poupei mais = so I saved more

So the original sentence is perfectly good Portuguese, but it has a slightly more careful or formal tone.

The comma separates the main statement from the result clause.

Structure:

• Eliminei a despesa supérflua = main idea
• de modo que poupei mais = consequence/result

In Portuguese, it is normal to use a comma here, especially with linking expressions like de modo que.

Poupei mais means I saved more. The comparison is understood from context.

It usually means:

• more than before
• more than I would otherwise have saved
• more money than previously

Portuguese often leaves this kind of comparison implicit when it is obvious.

If you want to be more explicit, you could say:

• poupei mais dinheiro = I saved more money
• poupei mais do que antes = I saved more than before

Yes. Poupar is a useful verb with more than one meaning.

Common meanings:

• to save money
  
  • poupar dinheiro
• to spare
  • poupa-me o trabalho = spare me the work
• to conserve / avoid using too much
  • poupar energia = save energy

In this sentence, poupei mais clearly means I saved more money/resources.

It is natural, but slightly formal because of:

• despesa supérflua
• de modo que

A more everyday European Portuguese version might be:

• Eliminei uma despesa desnecessária, por isso poupei mais.
• Cortei uma despesa desnecessária, por isso passei a poupar mais.

The original sentence is still perfectly correct and idiomatic, especially in written language.

Yes. Both are possible, but they are not exactly identical in tone.

• supérflua = superfluous, unnecessary, non-essential
• desnecessária = unnecessary

Supérflua can sound a bit more formal or stylistically refined.
Desnecessária is often more straightforward and common in everyday use.

So:

• a despesa supérflua
• a despesa desnecessária

Both work, but the second may feel more direct to many learners.

In European Portuguese, poupei is roughly pronounced like poo-PAY, but with Portuguese sounds, not English ones.

A few points:

• ou in European Portuguese often sounds like a closed o sound
• the stress is on the last syllable: -pei
• the final ei sounds like ay

So a rough guide is:

• pou-PEI

As always, the exact sound is different from English, but that approximation can help at first.