mjhjmtu

Can someone please explain the grammar use of 'de' in the sentence below? I understood 'de' to mean 'of the'.

Yo voy de compras todos los sábados. _{I go shopping every Saturday}

Would it not also be correct to say "Yo voy comprar todos los sábados"? I thought the 2nd verb had to be in the infinitive. Am I missing a gerund, perhaps?

Ir de... + noun is a pattern that you can use with a number of nouns. The meaning is about the same as the English "to go ...-ing". It has a connotation of planning or intent.

The word compra is a noun that means "purchase", "an act of buying". Ir de compras means "to go shopping", "to go on a shopping tour". It's in the plural because you'll probably shop for several items, and also because that's just how the phrase is used (it's a fixed idiom).

Other examples of this pattern:

• 
  ir de paseo = "to go for a walk" (or "to go for a ride", if in a vehicle)


• 
  ir de visita = "to go visiting", "to go on a visit" (ir de visita a lo de alguien = "to go on a visit to someone's house")


• 
  ir de viaje = "to go on a trip"


• 
  ir de copas = "to go out for drinks" (copas = "cups", figurative for "drinks")

For most of these you can use the verb in its pronominal form, with the "reflexive" pronoun: irse de compras, irse de viaje, etc., but not when speaking of habitual actions.

Me voy de compras. ¿Necesitas algo?

"I'm going shopping. Do you need anything?"

Generalmente voy de compras los sábados.

"I normally go shopping on Saturday."

Voy a comprar todos los sábados sounds wrong, mostly because comprar likes to have a direct object (the things that you're buying). Voy de compras solves this and allows you to be more general: you don't need to specify what you're buying, just that you're out shopping.

Finally, for many of these verbs you can replace ir with salir, with an almost identical meaning:

• 
  salir de paseo = "to go out for a walk"


• 
  salir de viaje = "to go on a trip"

The idea is the same, with the added connotation of "going out" (implying absence and distance).

"compras" is a noun there (the plural form of the noun "compra"), and "de compras" is a prepositional phrase more or less equivalent to "on a buying tour".

Alternatively, you can say:

• (Yo) Voy a hacer compras todos los sábados.


• (Yo) Hago compras todos los sábados.

or, as you said:

• (Yo) Voy a comprar todos los sábados. (Notice you need "a" between the verb "ir" and the infinitive that follows.)

In the first two examples above, "compras" is also a plural noun, meaning "purchases".

Other similar phrases are "de paseo" (for a walk) and "de excursión/viaje" (on a trip).

Small supplementary answer

You proposed

Yo voy comprar todos los sábados.

Let's change this a tiny bit to "I'm going to buy a kilo of flour" (to avoid the special thing with "de"):

Yo voy a comprar un kilo de harina.

The expression "Yo voy a [verb]" is a pattern that corresponds to "I'm going to [verb]."

Side note 1: As you may have learned, or might be learning soon, you can omit the subject pronoun "yo." In fact most of the time this is preferable, as it sounds more natural. (But as a beginner it's okay if you include it. Also, it would be included if one wants to emphasize who's doing the buying.)

Side note 2: "De" means of, from, etc. "Del / de la" means of the.