The step lengths table show the different measurements done. Then, the number of data in the table is the number of students that measured the step length. This is 18 (6 columns and 3 rows give 18 data since 6x3=18)
You can also see the graph and count every point in it, including the 28 that is far from the others. Each point represents a student.
Describing the graph that represents the distribution it can be seen that mosst students have a step length of 25 in (being this value the mode). The step lengths range from 21 to 28 and just few students had a step larger than 25 in. There is a value that was only reached by one student (28 in) being a value relatively far from the others.
Also the graph shows that most of the students have a step length between 22 and 26 in.