In math, a function is a set of ordered pairs in which each element of the first set (the domain) corresponds to exactly one element of the second set (the range). This table shows a function because each day of the week (the domain) corresponds to a specific number of children in the car (the range).

make this like a 8th grader wrote i t

In math, a function is when you have a list of days of the week and next to each day is a number of kids in the car. Each day matches up with just one number of kids, no more. Like Monday has 3 kids, Tuesday has 2 kids, and so on.