it is the number of times an outcome can occur compared to all possible outcomes
Outcome (probability) In probability theory, an outcome is a possible result of an experiment.[1] Each possible outcome of a particular experiment is unique, and different outcomes are mutually exclusive (only one outcome will occur on each trial of the experiment). All of the possible outcomes of an experiment form the elements of a sample space.[2]
Multiplicity (mathematics) The notion of multiplicity is important to be able to count correctly without specifying exceptions (for example, double roots counted twice). Hence the expression, "counted with multiplicity".