La mercancía llegó ayer.

Because Spanish often uses the definite article more than English does.

In La mercancía llegó ayer, la means the, so the sentence refers to a specific shipment or set of goods already known from the context.

Compare:

• La mercancía llegó ayer = The goods / the shipment arrived yesterday
• Mercancía llegó ayer = this sounds incomplete or unnatural in normal Spanish

So in this sentence, la is the normal choice.

Mercancía usually means goods, merchandise, or cargo, depending on context.

It is often a collective noun, so even though it is grammatically singular, it can refer to multiple items as a group.

For example:

• La mercancía llegó ayer = The goods arrived yesterday
• La mercancía está dañada = The goods are damaged

In business, transport, and logistics contexts, mercancía is very common.

Because Spanish and English do not always package ideas the same way.

In Spanish, mercancía is often treated as a singular collective noun, like a mass noun. Grammatically, it behaves as singular:

• La mercancía llegó
• La mercancía está aquí

Even if in English you would naturally say the goods, Spanish can still use singular mercancía.

Spanish can also use the plural mercancías, but mercancía in the singular is very common when talking about cargo or merchandise as a whole.

Llegó is the third-person singular preterite form of llegar.

That means it means:

• he arrived
• she arrived
• it arrived
• arrived

Here it matches la mercancía, which is grammatically singular, so the verb must also be singular:

• La mercancía llegó = singular noun + singular verb

If the subject were plural, the verb would change:

• Las mercancías llegaron ayer = The goods arrived yesterday

Because the sentence refers to a completed action at a specific time in the past.

The word ayer means yesterday, which strongly points to the preterite:

• La mercancía llegó ayer = The shipment arrived yesterday

The imperfect would not fit well here if you simply want to report the completed arrival. The imperfect is more for background, repeated actions, or ongoing past situations.

So:

• llegó = it arrived
• not llegaba = it was arriving / used to arrive

The accent mark shows where the stress falls.

Without getting too technical, mercancía is pronounced with the stress on -cí-:

• mer-can-CÍ-a

The accent is important because it tells you the word does not follow the default stress pattern.

It also helps show that í forms its own syllable here:

• mer-can-cí-a

The accent in llegó shows that the stress is on the last syllable:

• lle-GÓ

This is the normal written form of the preterite él/ella/usted form of many -ar verbs:

• habló
• trabajó
• llegó

The accent is not optional; it is part of the correct spelling.

Yes. Spanish word order is more flexible than English word order.

These are all possible, though they do not sound exactly the same in emphasis:

• La mercancía llegó ayer = neutral, straightforward
• Ayer llegó la mercancía = emphasizes yesterday
• Llegó ayer la mercancía = possible, often more literary or context-dependent

The original sentence is the most neutral and common way to say it.

In most of Spain, ll is pronounced like y in English yes, or something very close to it.

So llegó sounds roughly like:

• ye-GO

The exact sound can vary by region, but for most learners of Peninsular Spanish, treating ll like an English y is a good practical approach.

Yes, mercancía is a feminine noun, and that is why it takes la:

• la mercancía

Its adjective or article must agree with it:

• la mercancía retrasada
• la mercancía dañada

The ending -a often signals feminine gender, though not always. In this case, mercancía is indeed feminine.

Yes, but it changes the nuance slightly.

• La mercancía llegó ayer treats the goods as one shipment or one mass of merchandise
• Las mercancías llegaron ayer treats them as multiple goods/items/categories

In many real contexts, the singular mercancía is more natural when talking about a shipment, cargo, or merchandise in general.

Mostly yes, but with normal differences of usage between languages.

In this sentence, it works very directly:

• La mercancía llegó ayer = The shipment arrived yesterday

Spanish uses llegar for arriving at a place, reaching a destination, or coming in. It is a very common verb.

One useful detail: Spanish often does not need to state the destination if it is already clear from context, just like in English. So this sentence is perfectly complete on its own.