Comparamos la tarjeta de débito con la tarjeta de crédito.

Comparamos is the present indicative form of comparar for nosotros (we).

So it can mean:

• we compare
• or, depending on context, we are comparing

Spanish present tense often covers both the simple present and the present continuous idea that English sometimes separates.

Spanish often leaves out subject pronouns because the verb ending already shows who is doing the action.

• comparamos = we compare

So:

• Comparamos la tarjeta de débito...
• Nosotros comparamos la tarjeta de débito...

both are correct, but the version without nosotros is more natural unless you want emphasis or contrast.

For example:

• Nosotros comparamos la tarjeta de débito, no ellos.

Because comparar is a regular -ar verb.

In the present tense, the nosotros ending for -ar verbs is -amos:

• comparar → comparamos
• hablar → hablamos
• estudiar → estudiamos

So comparamos follows the normal pattern.

In Spanish, comparar is very commonly used with con when you compare one thing with another:

• comparar X con Y = to compare X with Y

So:

• Comparamos la tarjeta de débito con la tarjeta de crédito.

This is the most straightforward and standard way to say it.

You may also sometimes see comparison expressed in other ways, but comparar ... con ... is the safest and most common pattern for learners.

Spanish often repeats the article and noun more fully than English does.

So:

• la tarjeta de débito con la tarjeta de crédito

is completely natural.

In English, we might prefer to avoid repetition, but Spanish is often happy to repeat it for clarity.

You could shorten it in some contexts, for example:

• Comparamos la tarjeta de débito con la de crédito.

That means We compare the debit card with the credit one / with the credit card.

But the full version is very clear and perfectly normal.

La is the definite article: the.
Una is the indefinite article: a / one.

So the choice depends on context.

• la tarjeta de débito = the debit card
• una tarjeta de débito = a debit card

Spanish often uses the definite article in places where English might sound more general or abstract. In this sentence, la can refer to a specific card, or to the type/category in a general explanatory context.

If you wanted an indefinite meaning, you could say:

• Comparamos una tarjeta de débito con una tarjeta de crédito.

In Spanish, these types are normally expressed with de + noun:

• tarjeta de débito
• tarjeta de crédito

This is the standard way to name these cards.

So instead of something like debit card as a compound noun, Spanish uses:

• card of debit
• card of credit

That structure is very common in Spanish.

Tarjeta is a feminine noun, so it takes the feminine singular article la.

• la tarjeta
• plural: las tarjetas

That feminine gender stays the same even when you add de débito or de crédito.

So:

• la tarjeta de débito
• la tarjeta de crédito

both use la because tarjeta is feminine.

Yes, both words need written accents:

• débito
• crédito

The accent marks show the stress:

• DÉ-bi-to
• CRÉ-di-to

These are esdrújula words in Spanish, meaning the stress falls on the third-to-last syllable. Words of that type always take a written accent.

So the accents are not optional.

Yes, you can, but the meaning is slightly different in feel.

• comparar X con Y explicitly means to compare X with Y
• comparar X y Y means to compare X and Y

Both can be correct, but con makes the relationship more explicit and is especially helpful for learners.

So your original sentence:

• Comparamos la tarjeta de débito con la tarjeta de crédito.

is a very clear and standard choice.

Comparamos is pronounced roughly like:

• kom-pah-RA-mos

The stress falls on ra.

It does not need an accent mark because it follows the normal Spanish stress rules. It ends in -s, so the default stress is on the second-to-last syllable, which is exactly what happens here:

• co-mpa-RA-mos

Because the stress is regular, no written accent is needed.

Yes.

The Spanish present tense is flexible, so:

• Comparamos la tarjeta de débito con la tarjeta de crédito.

can mean:

• We compare the debit card with the credit card.
• We are comparing the debit card with the credit card.

Context tells you which meaning is intended.

If you want to make the right now idea extra clear, Spanish can also use:

• Estamos comparando la tarjeta de débito con la tarjeta de crédito.

But the simple present is still very common.

You would make the noun and article plural:

• Comparamos las tarjetas de débito con las tarjetas de crédito.

That means:

• We compare debit cards with credit cards.

You may also see a slightly less repetitive version, depending on context:

• Comparamos las tarjetas de débito con las de crédito.

Both are correct.