User story: data-property?

can anyone tell me what is meant by this user story:

. My counties should each have “data-fips” and “data-education” properties containing their corresponding fips and education values

The counties should have data-fips and data-education values that match the sample data

by properties do they mean variables Or object prop?

They are talking about HTML5 custom attributes. Custom attributes begin with data- and are meant to hold data about an element. According to the Javascript in the sample project, your appending a custom attribute, data-education, to an element which will be given a value that will probably be used by a tooltip.