The frequency of any value of any variable is the number of times that value occurs in the data. That is, a frequency is a count.

The relative frequency of any value is the proportion or fraction or percent of all observations that have that value.

Data are univariate when only one variable is measured on each unit.

Data are bivariate when two variables are measured on each unit.

Data are multivariate when more than one variable is measured on each unit.