Frequency and Relative frequency, (Counts and percentages)

Frequencies are probably the most popular statistics.

A frequency is nothing more than a count.
And a relative frequency is a percentage.

Thus if we have a sample of 10 marbles we may count
4 red marbles
3 green marbles
2 blue marbles
1 yellow marble

The 4,3,2,1 are their counts or frequencies and their relative frequency would be the percentage they represent of the sample of 10.

We find a percentage dividing the count by the sample size, like
4/10 = 0.4 or 40%
4/10 = 0.2 or 30%
4/10 = 0.3 or 20%
4/10 = 0.1 or 10%

Data like this is often seen in the form of a bar chart, or a pie chart and is one of the most popular ways to present data for drawing conclusions.