The sample size is the number of people.
You can get the sample size by counting the completion times for each.
Sample size of men = 19
Sample size of women = 34
The mean time is the average time, so you need to add all the times for the men and divide it by the number of men and then the same for the women:
Mean time for men = 3129 / 19 = 164.68 seconds
Mean time for women = 5834 / 34 = 171.59 seconds.
The mean time taken by men is less than the women.