This is a great quote from Silver Linings Playbook, which is a good movie about mental health with complex depictions of Bipolar and grief.
We all have different parts or aspects to ourselves. One of the tasks of infant development is actually integrating these disparate parts into a sense of a unified self. That being said, we all still have these parts or aspects to ourselves even in adulthood. Who I am as a therapist is one part of myself and who I am as a dog mom is another part of myself and who I am as a daughter is yet another part of myself.
If there has been trauma in a child’s life, such as neglect, abuse, or a toxic home environment then there may be less of a unified sense of self. And it is very common in this situation to have aspects of self that are experienced as dirty and shameful. For some folks it might be the angry side of themselves as it reminds them of an angry and out of control parent. For some it is the side of themselves that wants affection and love, because in their home love was seen as weakness or played upon by a predator.
However, in order to heal and lead full lives we need to learn to come to terms with these disavowed or hated parts. These are all necessary and valid parts to ourselves and finding a way to accept them is incredibly important. Therapy is often helpful in learning how to love all the aspects and parts of yourself.