The graph shown in the image is a box and whiskers plot.
The sides of the box are determined by the first and third quartiles of the sample.
The left side corresponds to the first quartile (Q₁), this value separates the bottom 25% of the sample from the top 75%
The right side corresponds to the third quartile (Q₃), this value separates the bottom 75% of the sample from the top 25%
The line inside the box represents the second quartile (Q₂), this value is also known as the Median of the sample and divides the bottom 50% from the top 50%.
The body of the box, i.e. the space between Q₁ and Q₃, is the interquartile range (IQR), this represents the mid 50% of the sample.
The left whisker links the first quartile with the minimum value of the sample.
The right whisker links the third quartile with the maximum