What does the black goddess statue do and what is it?

In Hateno village, there is a boy you can talk to and he brings you to the statue. All I know is that it takes away a heart container. Does it do anything else and what does it represent?

Based on your explanation, you are at the beginning stage of the quest The Statue's Bargain. The statue steals either a heart container or stamina vessel, and the quest is regain whichever the statue took from you.

After you finish the quest, the Horned Statue will allow you to exchange heart containers for stamina vessels (and vice versa). This is designed to reallocate your stats as you see fit after already increasing them with spirit orbs.