Does anyone knows what "Df", "Sum Sq", "Mean Sq", "F value", and "Pr(>F)" stands for when we print a summary of an aov() output? I know it gives information about how groups are linked together but, does Mean Sq is the mean of the values from source 1 or from source 2? Or is it the difference between those 2? Or is it something else? I get what is the Sum Sq, mean Sq, F value, etc for a single group of data but what does it means when we compare two groups?
Here's an example of a summary.aov() for data representing the weightgain for beef/cereal(source) and high/low(type):
