OCR stands for Optical Character Recognition. In Elite Dangerous this was the very early days of 2014 to capture market data from a screenshot and convert it to TEXT data to be manipulated in various ways for example sending it to EDDN etc.
This tool has been made obsolete with introduction of community API using tools like EDMC and others. EliteOCR page exists for historial reasons.
EliteOCR is the utility to use to grab market data from screenshots and export it to EDDN to be shared with the community. It also export it to CSV file format which you can keep in your hard drive, however it is preferred that you always export to EDDN.