Normal vision is 20/20 in the nomenclature of Dutch ophthalmologist Herman Snellen. In 1862, he calibrated a set of descending-sized letters to the eyesight of his young assistant, who was presumed to have normal vision. From a distance of 20 feet, the smallest letters the young man could read were designated 20/20. There are a few people who can read letters half that size, or 20/10, from the same distance.
http://bluestream.wustl.edu/WhitakerArchives/00_annual_report/theeye.html
No need to “discuss” facts that can be looked up. 
20/20 means that at 20 feet things are as clear as this standard’s “normal.” 20/400 would mean that at 20 feet things look as clear as 400 feet relative to the standard’s “normal” eyesight. So no, 20/10 does not mean that you are far sighted. It means that at 20 feet you see things as clearly as a “normal” person would see at 10 feet. You may also see clearly at close distances, or you may actually be farsighted. The rating does not specify.