The Mean is the value of all the numbers in a data set added together and divided by the amount of numbers there are for example the mean of the set 2,5,8,9 is 6.
The median is the middle values of all the numbers. If there are 2 medians, you usually have to add them both and divide by 2 to get the actual median
The mode is the number(s) that show up the most in the data set. for example, the mode of the data set 2,2,3,4,4,4,6,9 is 4, because it is repeated 3 times.
hope this helped!