Using datives and accusatives together

[elpasajero]

There is this one phrase that is hard to get:

"Le preparas la cena? Sí se la preparo."

Do you cook the dinner? Yeah I cook it. Thats what google translator says.

Another example: "Le das el dinero? No, no se lo doy" translator says: "Do you give him money? No I don't give it to him".

What I don't get here is how this is done: Le preparas la cena? no no se la preparo. But I keep missing the point.

How do you use this structure in spanish? It has to do with combining datives and accusatives together, but I do not get how:

"Les Mandas las flores? Sí, se las mando"

Can you give some examples about using these accusatives and datives together and how to think about it?

[Rusty]

The important thing to grasp here is that 'se' replaces 'le' or 'les' when a second pronoun starting with 'l' immediately follows, to avoid cacophony. The pronoun 'se' will always appear prior to the other pronoun.

¿Le preparas la cena? (note the inverted question mark)
Are you cooking the dinner for him?
Sí, se la preparo.
Yes, I'm cooking it for him.

¿Le das el dinero?
Are you giving him the money?
No, no se lo doy.
No, I'm not giving it to him.

¿Les mandas las flores?
Are you sending them the flowers?
Sí, se las mando.
Yes, I'm sending them to them.