La fecha de caducidad de esa leche es mañana, así que mejor compra otra marca.

Fecha de caducidad is a fixed, very common expression meaning expiry date or use-by date.

• fecha = date
• caducidad = expiration / expiry

So la fecha de caducidad de esa leche literally means the expiry date of that milk.

In everyday Spanish, people may also shorten things depending on context, but fecha de caducidad is the standard full phrase you will often see on packaging.

Yes, in this context caducidad refers to the point when a product should no longer be consumed or used.

In Spain, caducidad is commonly used for products that become unsafe after a certain date, especially food. You may also see:

• fecha de caducidad = expiry date / use-by date
• fecha de consumo preferente = best-before date

That distinction matters in Spain:

• caducidad = after this date, it may be unsafe
• consumo preferente = after this date, quality may be worse, but it is not necessarily unsafe

Because Spanish often uses de to link nouns together, where English might use of or a noun modifier.

Here the structure is:

• la fecha de caducidad = the date of expiration
• de esa leche = of that milk

So the full phrase is literally:

the date of expiration of that milk

This sounds normal in Spanish, even if English would usually compress it into that milk’s expiry date.

Both are possible, but they mean slightly different things.

• esta leche = this milk
• esa leche = that milk

Spanish demonstratives reflect distance or psychological distance:

• esta = near the speaker
• esa = near the listener, or a bit removed from the speaker
• aquella = farther away

So esa leche suggests that milk, perhaps the one the other person is holding, looking at, or considering buying.

Yes. Even though leche is usually uncountable, Spanish often uses the product name to refer to a specific container of it.

So esa leche can naturally mean:

• that milk in general, or
• that carton/bottle of milk

This works just like English, where you might say That milk expires tomorrow, even though you really mean that carton of milk.

Because with days and many time expressions, Spanish usually does not use a preposition like in.

So you say:

• Es mañana = It is tomorrow
• Es hoy = It is today
• Es el lunes = It is Monday

English often needs a different structure, but in Spanish this is completely normal. The verb ser links the subject (la fecha de caducidad) with the time expression (mañana).

Because mañana here is being used as the adverb tomorrow, not as a noun.

Compare:

• Es mañana. = It is tomorrow.
• La mañana es fresca. = The morning is cool.

So:

• mañana = tomorrow → no article
• la mañana = the morning → article needed

Context tells you which meaning is intended.

Así que means so, therefore, or so then. It introduces a consequence or conclusion.

In the sentence:

La fecha de caducidad de esa leche es mañana, así que mejor compra otra marca.

it means:

That milk expires tomorrow, so you’d better buy another brand.

It is a very common connector in spoken and written Spanish.

They are similar, but not identical.

• así que = so / therefore
  Very natural for linking cause and result in one sentence.

• por eso = for that reason / that’s why
  A bit more explicit.

• entonces = then / so
  Very common in speech, sometimes a little looser or more conversational.

In this sentence, all three could work in some contexts, but así que sounds very natural and direct.

For example:

• ..., así que mejor compra otra marca.
• ..., por eso mejor compra otra marca.
• ..., entonces mejor compra otra marca.

The first is probably the most straightforward here.

Yes. Here compra is the tú imperative of comprar.

• compras = you buy
• compra = buy! (informal singular command)

So mejor compra otra marca literally means something like:

better buy another brand

In natural English, that often becomes:

you’d better buy another brand or it’s better to buy another brand

Spanish has several ways to give advice. This sentence uses a direct, natural spoken pattern:

• mejor compra otra marca = better buy another brand

Other possible versions include:

• mejor compres otra marca → generally not standard here
• mejor compra otra marca → natural
• es mejor que compres otra marca = it’s better that you buy another brand
• será mejor que compres otra marca = you’d better buy another brand

So after mejor, Spanish often uses a direct imperative for practical advice.

Because Spanish usually leaves subject pronouns out when they are not needed.

So:

• compra otra marca = buy another brand
• tú compra otra marca = you buy another brand

The second version sounds more emphatic and would only be used in special situations. Normally, the verb ending already tells you that the command is for tú.

Because otro / otra normally replaces the indefinite article.

So Spanish says:

• otra marca = another brand
• not una otra marca

This is the normal rule in Spanish:

• otro día = another day
• otra vez = another time / again
• otro problema = another problem

Because marca is feminine:

• la marca
• otra marca

Adjectives and determiners must agree with the noun in gender and number.

So:

• otro producto
• otra marca
• otros productos
• otras marcas

Yes, absolutely. That is a very natural alternative.

• La fecha de caducidad de esa leche es mañana = The expiry date of that milk is tomorrow
• Esa leche caduca mañana = That milk expires tomorrow

The second version is shorter and often more natural in everyday speech. The original sentence sounds a bit more explicit, as if focusing on the date shown on the packaging.

Because así is a word that normally carries a written accent according to Spanish spelling rules.

• así = like this / so

But que here is just the conjunction that/so, and it does not take an accent.

Compare:

• que = that / which / so
• qué = what

So in así que, there is no accent on que because it is not a question word.

Yes, it sounds very natural in Spain, especially because of fecha de caducidad, which is very common on food packaging there.

Also, the use of compra as a tú command fits informal peninsular Spanish well. In Spain, if you were speaking formally, you would say:

• mejor compre otra marca

And if speaking to several people informally in Spain, you might say:

• mejor comprad otra marca

So the original sentence clearly sounds like informal singular advice.