A single quote in excel is used to maintain formatting of the data enterd in the field. Or better yet, to ignore formatting and read it as text.
For example, if you want to enter ( = $5.00 ), excel will assume you are trying to enter a formula and will return an error. If you wish to display the data as it appears above you must enter a ( ' ) at the begining.
when you hit enter, the (') will disappear, displaying only the text after the apostrophe
Hope I didn't make that too complicated.