A Ramdom variable is a function that assigns a numerical value to every possible outcome in a sample space.
It is a number that represents a result of an event or a random experiment. This variable does not depend on other factors and its values are random, without a specific order. For example: when you roll a dice, the number that you get is a random variable, because in 6 attempts you may get 1,6,4,2,2,5 and then, in another 6 attempts, you may get 3,3, 6,2,1,6.