Identify Fractions uses number lines to demonstrate the meaning of numerator and denominator.
The following illustration was made by Identify Fractions Designer
The distance from 0 to 1 is a unit. This unit is divided into 5 equal parts. The arrow tells us that 2 of the parts are chosen. The chosen parts are colored red.
The top number 2 in the numeral is the numerator. The numerator tells us how many parts are chosen.
The bottom number 5 in the numeral is the denominator. The denominator tells us the total number of equal parts into which the unit is divided. In this example there are 5 equal parts in the unit from 0 to 1.
The line between the numerator and denominator is known as the fraction bar. It is also called the division bar.
You will enter the fraction because the arrow points to the 2nd of 5 parts.