My Mum never helped me with my homework, I don't think she often understood it! My grandmother taught me to read and write before I ever started school, and I remember my granddad helping me to understand multiplication and division, and then I was told off for doing it a different way to what we were taught! I never had homework at primary of junior school, only in secondary school.
We helped our children with their homework when we were able to and when they asked for help, which wasn't often, but we never did the work for them. Usually it was spellings, history, geography, maths or research or providing materials for creative projects. When my eldest son was studying Art & Design he remembered one morning that he needed some paintbrushes for his lesson - so he took some of mine. His teacher noticed what he was painting with, and asked where he had got them. When he told her she took my best Sable watercolour brushes off him, carefully cleaned them and gave him something more suitable!
We live too far away to be able to help our grandchildren who are all at the Primary/Junior stage, but their parents help as much as they can with reading, writing, maths, spelling and projects etc. They often spend the best part of the evening on homework, only stopping when it's bedtime. Far too much homework! Personally I don't think children of that age should be given homework at all. After a long day at school they need time to socialise and relax with their families.