Suppose that you want to graph the heights and weights of a group of people. Since both height and weight are variables, we use the phrase bivariate data, meaning that there are two variables (height and weight). Bivariate data are best displayed on a Scattergram (aka Scatter Plot). To construct a scattergram, follow the instructions in my video below:
I used scattergrams a lot in my PhD research to compare populations of the painted topshell Calliostoma zizyphinum. They are an excellent way to see differences in populations. My scattergrams were drawn using SPSS v2 on a DEC 20 mainframe computer - at that time (1984-1987) the small Computer Science Department in Trinity was the Brunswick Chambers building at 200 Pearse Street. I had to learn some FORTRAN programming to feed my data files into SPSS, and then wait until the next day to see the results on a printout which was placed in a pigeon hole style box for collection. No instant results in those days.
I'm certain that if I had Excel that I would have been able to shave months off the time (4 years) it took me to complete the PhD - data analysis has become a lot faster and easier with fantastic tools like Excel.