What is the meaning of filial disobedience (ʿuqūq al-wālidayn), and is refusing to do a simple thing that the mother asks considered an act of disobedience?

A son must honor his parents and obey them in what is good. However, there is no obedience to them in disobeying the Creator, nor in what exceeds his capacity. It is not permissible to disobey one's mother or go against her command if the son is able to fulfill it and it causes him no harm. Disobeying parents (al-'Uquq) is one of the gravest sins. Allah has commanded kindness to parents and forbidden harming them, even with the word "Uff," and He commanded speaking to them with noble words.