Why is it ayudarle and not ayudarlo?

Why is it ayudarle and not ayudarlo?
 

Puedo ayudarle means I can help you. But why is it Le? Le is for indirect objects. You is the direct object of the sentence. What am I missing here?

'Ayudar' takes a direct object, as you stated, and, therefore, you should use a direct object pronoun. That said, the indirect object pronoun 'le' is used in certain regions.
If you see 'ayudarle', this is a form of leísmo. It is defended where it is used, so you shouldn't get into any fights over its use. ;) When you find yourself among those who say 'ayudarle', you'll find that some of them will switch to 'ayudarla' if the direct object is a female. They just prefer 'ayudarle' over 'ayudarlo'.