Lo, "it", is a direct object pronoun and can be place in one of two positions in a sentence or phrase. The first position, and probably the most common, is directly before the first verb in a sentence or phrase.
I'm still having trouble grasping the clitics it seems. I put "ella ha hecho a muy bien.".... using "a" after hecho instead of "lo" before it. Is that weird sounding or poor grammar or just plain wrong?