They provide tailored support to help people meet their personal and social needs, which could include bathing, meal preparation, using the toilet, shopping, and leisure activities. They may also be required to help to use certain types of equipment or to assist with things that are better done with the help of another person.
The amount of assistance needed depends on the person's disability and can vary from a few hours a week to full time support. As a PA you would support the person you work for to be in control of their own choices, not to make choices for them. An understanding and appreciation of empowerment and citizenship is very important in this role.