why does decir use pronouns in conjugation
puedo decirle
5 Answers
First, thanks for the question, Warbo, and thanks to Ian, Gringojrf, Pescador & Fraan for the stimulating discussion. I am learning a lot.
So, I was forced to do a search for more information. Here is an article: Verbs Used With Indirect-Object Pronouns: Usage Common With 'Gustar'-like Verbs, Verbs of Communication link
Quote: "Verbs of communication: It is common when using verbs of communication — examples include hablar (to speak) and decir (to tell) — to use indirect-object pronouns. The logic behind this is that the speaker is communicating something, and that something is the direct object, and the person spoken to is the recipient."
Pescador you are correct. The direct object in implied. Sorry.
Decir often uses indirect object because something is being told TO somebody. In the example you have given "decir" is not conjugated, but in it's infinitive form. Here are some other verbs that are frequently associated with indirect objects/indirect object pronouns: dar, pedir, recomendar, preguntar, traer, mandar, escribir, prestar, regalar. Basically, the indirect object receives the action of a verb and answers the questions to whom? or for whom?
Le/Te puedo decir o Puedo decirte/decirle. Both are possible 
puedo decirle = I can tell you.
You can connect / add the pronoun to the end of all infinitive verb forms.
