A Stem and Leaf Plot is a special table where each data value is split into a "stem" (the first digit or digits) and a "leaf" (usually the last digit).
For example "32" is split into "3" (stem) and "2" (leaf). The "stem" values are listed down, and the "leaf" values are listed next to them.
The "stem" is used to group the scores and each "leaf" shows the individual scores within each group.
It is a method for showing the frequency with which certain classes of values occur.