Consider the data set 2, 3, 4, 5, 5, 5, 7, 8, 8, 8, 10. The values 5 and 8 both appear three times. When you have two candidates for the mode like this you say the data is bimodal. Usually when you have more than two candidates for the mode you say there is no mode. Other people may tell you something slightly different. Happily it is not something for you to worry about.