What is a row crop head?

In this case, the Word "head" is an abbreviation for header. A header is the implement mounted to the front of a combine harvester to reap and gather the crop for threshing in the middle part of the machine. A row crop header is a header designed specifically for harvesting crops which are planted in individual rows. In the midwestern US, this is typically corn. A row crop header for harvesting corn can be seen in the related link below. I just randomly picked one brand of combine harvester -- no implication pro or con to the brand.