Why is 'se' needed in this sentence

Question

I never would have known to use 'se' in this sentence. Something I'm not good at I guess. Is there an easy way to know?

"Si yo hubiera sabido la respuesta, se la habría dicho."

Answer 1

If I had known the answer, I would have told it to him/her/you (usted), them/you (ustedes)

"se" is the indirect object pronoun used with "decir". "le (him/her/it)" or "les (them/you [ustedes])" becomes "se" when it comes before "lo","la","los" or "las". Looks like the reflexive pronoun, right? It wouldn't be nice to get that confused...

• Ahhhhhhhh yeah, I see it now. Thank you! - Erin Jul 26, 2011
• No problem, great to see you again, Erin :) - GuitarWarrio Jul 26, 2011

Answer 2

I've seen it referred to as the "la la" rule.

To keep two object pronouns starting with "L" from being next to each other, you change the first to "se" as mentioned above.