What does the "se" mean in the following sentence and why is it there. I know about reflexive verbs and the pronouns, but i can't figure out why it is there in this case because I didn't think "dar, to give" was a reflexive verb.

Se las he dado.

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Yes, indeed 'se' is a pronoun, is reflexive for the pronouns 'he' or 'she':

Se pegó en su codo = He/She (himself/herserlf) hit his/her elbow

But it's also a reciprocal pronoun, in this case 'se' replaces the pronoun him, her or them in English:

I (gave it) to him, I (gave it) to her, I (gave it) to them

The word 'las' in your example it's also a pronoun that remplaces 'the things' you are giving, and I say things because 'las' is plural, and 'la' singular.

Also you can say:

Se las di (changing the verb tense)

“Las he dado” means you gave something to someone... “Se” answers the question ‘To whom?’... “Se” is a form of third person pronouns (el, ella, ellos, ellas). So in “se las he dado” you are saying that you gave something to someone different than the person you’re speaking to.

@averybroom Yes it is possible to use 'le':

Le he dado

But in this sentence it's not said 'what', which in the other sentence was implicit by the pronoun 'las', you would have to specify:

Le he dado las '(femenine plural noun)'

Or

Le di las '(femenine plural noun)'

@averybroom You can use both direct and indirect object pronouns at the same time, this is how your initial example is written: "se (indirect object) las (direct objet) he dado ( verbal tense)".

You can also use the pronouns separately:

He dado (I've given)
Las di (I gave them)
le di (I gave him, I gave he, I gave you (usted))

But in these last examples you are not saying what you are giving... To say what you are giving you must add the noun along with the correspondent article; el, la, los, las:

Le di las llaves a Susan = I gave the keys to Susan

In this example 'las' it's not a pronoun, it's an article.

Se las he dado.(Las flores)

Las he dado a ella. (Las flores )

He dado a ella flores.

A ella le he dado las flores.

(A ella) se las he dado.

Se las he dado.