"The Colossus" takes us through a day in the life of a person who spends her time taking care of a huge, shattered statue. What does one do to take care of a huge shattered statue, you ask? Well, the speaker mostly does some cleaning here and there, and tries her best to put it back together again. She knows it's a hopeless task, but she just can't seem to stop doing it.
Throughout the poem, there are hints that the whole thing is an extended metaphor for a woman who's dealing with emotional damage caused by the loss of her father. Ultimately, she's well aware of the unhealthy nature of her situation, but she seems resigned to the fact that this is how she lives.