Count, CountIF and CountIFS Functions

COUNT Functions

The count functions can be used to count text or numbers in a Spreadsheet. The basic function is:
=COUNT(cell reference range)
=COUNT(B2:B5)

For counting more complex criteria or data we tend to use the CountIf or for multiple criteria and comparisons we use CountIFs:

=COUNTIF(cell reference range, "criteria")
=COUNTIFS(B2:B5,"=Yes")

=COUNTIFS(cell reference range, "criteria",cell reference range "criteria")
=COUNTIFS(B2:B5,"=Yes",C2:C5,"=Yes")

Source:
https://support.office.com/en-us/article/COUNTIF-function-e0de10c6-f885-4e71-abb4-1f464816df34