A number line is a straight line that represents numbers in a visual way. It usually has a zero in the middle, with positive numbers extending to the right and negative numbers extending to the left. Each point on the line corresponds to a specific number, making it easy to see the order and distance between numbers. Using a number line helps with basic math concepts like addition and subtraction. For example, if you want to add 3 and 2, you can start at 3 on the number line and move 2 spaces to the right, landing on 5.