Norm, I think, refers to common practices, beliefs and trends. As an African person, I grew up to discover that we have several norms that we follow daily, week in week out. For instance, when you wake up in the morning, you must greet everyone, especially the elders. Why I stressed on the elders is that if you don't greet the elders it will be counted for you as an offense.
And then, you go on to perform your morning household chores. Yours might be to go and do the dishes, or to go and fetch water or to sweep the compound. Everyone of us grew up with these norms. We do not need to think of what our day will look like, we already know what we are to do when we get up.
These cultural norms cover much more in our life cycles. We have certain trends and practices to carry out while growing for us to acquire education. We have those ones we do when we are about to get married. We equally have those ones we observed as parents while raising our children. These are the norms in our society and culture.
One thing stands out, these norms make us better persons. In fact maturity and home training is measured using these norms as the yard stick.