Excel has three basic counting functions, and they're easy to mix up.
COUNT counts cells that contain numbers. It ignores text, blanks and words like "n/a".COUNTA counts cells that are not empty: numbers, text, anything.COUNTBLANK counts the empty cells.
So in a column of names, COUNT returns 0, because names are text. Use COUNTA to count people and COUNT to count how many have a number entered.
Counts combine well with other formulas. =COUNT(C2:C13)/COUNTA(A2:A13) gives the share of people who submitted a number.