To be superior in strength, dominance, influence or frequency; to have or gain the advantage over others; to have the upper hand; to outnumber others.
Red colour prevails in the Canadian flag.
To be current, widespread or predominant; to have currency or prevalence.
In his day and age, such practices prevailed all over Europe.
To succeed in persuading or inducing.
I prevailed on him to wait.
To avail.