To graph the data set, you have to choose the scale for the x-axis and the y-axis, then plot the points and link them with a line.
I chose a 1 to 10 scale for both axis:
The x-axis represents the time, measured in hours, and the y-axis represents the population, measured in millions of bacteria. The graph represents the bacterial growth with respect to the time.
In this case, the graph starts at point (0,2) because at the start of the experiment, the population of bacteria was 2 million.
When you perform an experiment where the independent variable is the time, the starting time is usually considered as t=0. Because it is at this point that the clock starts, and you use it as a reference to record how much time passes between measures.