probability is the number of chances an event is likely to take place.
We find it by the formula :-
Number of possible outcomes / No of total outcomes.
eg. What's the probability that a no. appearing on the dice would be a multiple of 2?
There are 3 possible outcomes - 2, 4, 6.
But there are 6 total outcomes - 1, 2, 3, 4, 5, 6
Therefore the probability is 3/6 or 1/2.