I have a spreadsheet which contains 1,000 rows - each row has a date of birth

I would like to find out how many rows have the month of Apri 2014, May 2014, and so on.

Is there a easy way to do this?

The easiest way is to create a pivot table based on the data table.

Add the date field (column) to the Rows area and to the Values area.

Right-click one of the dates in the Rows area, and select Group... from the context menu,

Group by year and by month.