The data consists of 25 observations - this is just how many people were involved in the study. (count the rows, excluding the header)
As for number of variables, that depends on the aim of the study. More likely than not, I suspect the name of each person involved is irrelevant, which leaves 7 variables. (count the columns, excluding the first)
65 millimeters to meters is .065 and you would know this because there's .001 millimeters in 1 meter so with 65 you would move the decimal up 3 spaces o make .065m
