mode = the most common value. So if your data is (1,1,1,2,3,4,5) the mode is 1.
median = the middle point of the values so the median of the above set would be 2.
mean = the sum of all the values divided by the number of values there were, so it'd be 2.429 for that dataset
range = the difference between the highest and lowest value, subtract the lowest from the highest and you have it. For example the range of that dataset is 4.