I can’t understand why it is le digo and not lo/la digo. Le is an indirect object pronoun. The sentence given was simply Le digo which Duolingo translated as I tell you or I am telling you. So why the indirect object pronoun. I is the subject telling is the action so you is a a direct object. I must be wrong so can someone explain whyplease.
Hi! No, "you" is not the direct object. It's the indirect object. The direct object is the thing that "suffers" from the action, i.e. the thing that is being said. So, if we extend the sentence to "I tell you the truth" or "I tell you the news," it becomes obvious that "the truth" and "the news" are the direct object and "you" is the indirect one. Good luck!