In my opinion, if you look at the first dot plot, the dots are spread out somewhat evenly between 4 and 16 with a center of about 10 and a slight pull to the left. since they are spread evenly with slightly more on left it can be assumed that the mean (also known as average value) would be slightly left of the center 10. this would be 9.
The bottom plot has a tighter pattern but it also looks as though it is spread out evenly but slightly left of its center of also 10. this would make the mean 9 as well
If the dot plots appear to be centered the same it can be assumed the means are the same.
to get the means you would add up the dots values on top plot and divide by amount of dots. same for bottom plot.
top mean = 9
bottom = 9