From my own experience working at a CNA before starting PA school, my responsibilities included helping patients or residents with eating, toileting, bathing and other hygiene such as shaving, checking vital signs and blood glucose, and basic documentation on what I did during shifts. There may well be variations in your responsibilities depending your level of experience, type of work setting, etc., and you still certainly be given a list of responsibilities as part of interview or orientation/training process. I hope this helps.
Nursing Assistants provide basic direct (face-to-face, hands-on) patient care in nursing homes, assisted living facilities, private homes, rehabilitation centers, Adult Family Homes (AFH), Behavioral Health Centers, and Acute Care Centers (Hospitals).
Nursing Assistant (NAC or CNA) Programs are offered at many high schools as elective courses, at community colleges, by long-term care facilities (who will often pay tuition) and through small businesses. The advantages of becoming a Nursing Assistant are many- it is a quick first step into Nursing, provides the opportunity for job experience in patient care and looks great on a Nursing program application- in fact, many Nursing programs are giving admission preference or requiring applicants to have attended a Nursing Assistant Program.
It's also a great way to see if Nursing is for you, or if you prefer to pursue a different area of healthcare.
Best of luck to you!