Chase Urhahn, great tips from Charlotte Irwin. I just wanted to add that if you are trying to quickly identify on a county tax delinquent list which properties are vacant, versus have some substantial improvements on them (house, etc.), there are often at least 3 separate columns/fields for each property's assessed values of: Land, Improvements, and Total Value or Net Value (and sometimes a fourth like, "Other").
So if you are trying to market to owners of vacant land only and you have the list in Excel, you can use the Filter function to exclude any rows (properties) that have an assessed value in the Improvements field above a certain value, as low as $0 if you want (although some "vacant" properties might have a couple hundred or even a couple thousand dollars worth of improvements, like a driveway, or existing well or septic, a fence, storage building, etc.).
Interestingly, in your screenshot I see a field for Land assessed value and Net assessed value, only. It's possible the Improvements field is just out of the field of view in that picture, but if by some chance that county actually doesn't report the assessed value of Improvements (which would be a bit unique in my experience), again assuming you have their tax delinquent list in a format you can open and manipulate in Excel, you could just insert a new column and enter a formula in that column that subtracts the Land value from the Net value for each row. Then treat that difference between the two like it's the Improvements value, because for our intents and purposes it probably is.