In the context of the data provided, the y-axis label of the scatterplot would represent "Texting speed (words per minute)."
Typically, in a scatterplot, the independent variable is plotted on the x-axis and the dependent variable on the y-axis. In this case, time (in minutes) can be considered the independent variable, while the texting speed (in words per minute) would be the dependent variable that is influenced by the amount of time spent texting.
So the y-axis label of the scatterplot is Texting speed (words per minute).