A CSV or Comma Seperated Value File is essentially a flat file database. It is just a text file that can be opened in Notepad with each record on a new line, and the columns seperated by a delimiter usually a comma hence the name. They are useful in that they are universally recoginsed by all database and spreadsheet applications on nearly every computing platform.
A CSV file would look like this:
customerid,customername,customeraddress
0001,bob,here
0002,jim,overthere
0003,dave,anywhere
Sometimes, if there are commas in the data, you can surround the data with quotes or use an exotic delimitersuch as ¬ which wont be in the data.
If you have the data in Excel, you can do a Save as Text from the File menu to make one. Or you can use the export feature in Access under File - Export after selecting a table if you have the data in an Access database.
Alternativly, if the data sample is small and you have a spare member of staff you dont like very much, you could get them to type it up in Notepad and just save the file with a .csv extension.