The values for those fields would usually be a boolean indicating whether you voted or not. For a primary it might have the party, meaning which party's primary you voted in.

For a Get Out the Vote operation it's very valuable to know how consistently people have voted in the past. If you look like a supporter but you vote inconsistently, I might call and ask if you need a ride to the polls. If you already vote every time, I'll allocate resources elsewhere, or ask you to donate/volunteer.

It's probably whether or not you voted in those races, not who you voted for.

That said, both RNC and DNC databases track who you are likely to have voted for in each race, but that's just a guess. It's a secret ballot. Nobody knows who you voted for.