If you can’t interpret a plot, that is not your problem, but the fault of whoever made the plot! Graphs should be made to highlight information not obscure it.
If you are having trouble interpreting a graph though, start by reading the title and labels. You need to know what physical processes the data represents. Once you understand the background information for the plot, look for correlations or patterns within the data. These will depend on the type of plot, but as an example, if a scatter plot forms a straight line sloping upwards, it indicates a positive relationship between the x and y variable. In the following plot, there is a positive relationship between energy and size. As size increases, the energy increases as well.
I won’t run through every kind of plot here, but there are resources available online for learning more about graphs. Khan Academy has great videos on making and interpreting plots. For a more rigorous take on graphs and visual presentation, check out the The Visual Display of Quantitative Information by Edward Tufte.
Hope that give you a start!
