Newbie had Deed question

[Kaci Hunter]

A house I'm interested in buying is 6 years behind on taxes. Additionally, when checking with the appraisal district, the deed says "warranty deed/vendor lien." What does this mean? I'm new at this and ignorant. Speak in laymen's' terms, but be detailed, please. Also, I'm not sure if I want to wholesale or fix and flip. So the typical formula is 70 % of ARV- repair costs, but how do you factor in back taxes and liens...?