The COUNT function is a simple function that counts numbers.
Let's take a look.
The COUNT function counts numeric values. For example, if I enter the formula =COUNT(B7:B11), Excel will return "4" because that range contains four numbers total.
The COUNT function ignores blank cells and text values.
The formula =COUNT(D7:E9) will return "3" because COUNT treats the date, time, and percentage as numbers.
A good way to check the actual value in a cell is to temporarily apply the General format. You can then easily see which values are numbers.
Negative numbers are counted, too.
The COUNT function accepts one or more values, up to 255 total, separated by commas, so I can easily enter all previous values individually and get a total count.
Like other functions that accept multiple values, you can hold down the Control key (Command key on the Mac) and Excel will add the commas for you, each time you click a new location on the worksheet.
Note that if you want to count text values, you'll want to use the COUNTA function.