Okay kiddo, have you ever heard of crops? They are things that farmers grow in their fields, like corn or wheat. Nonfood crops are plants that are grown but not to be eaten (like fruits and vegetables). Instead, they are grown for other purposes, like making clothes or fuel.
Let's take an example of cotton. Cotton is not something we eat, but we use it to make clothes and other textile products. Similarly, some plants are grown to make oils that we use for cooking or to make biodiesel fuel for our cars.
Nonfood crops can also be plants that are used for their medicinal properties. These plants can be used to make medicine that helps people when they are sick.
So, basically, nonfood crops are plants that are grown for purposes other than for people to eat. They are used to make clothes, fuel, medicine, and many other things that we use in our daily life.