"proximity" is an English word meaning "nearness" - being close to something. See a dictionary for exact definition. It is often relative what is "near" - for example you may have a shop in your proximity, meaning for instance withing a walking distance, or a hard disk head is flying in proximity to the disk surface - maybe just some fractions of a micrometer. Got an idea what the word means?
In electronics you have likely heard of "proximity switches," and "proximity detectors." Those are sensors which do not need physical contact to operate. And, yes, many of those work by magnetic principles, but they may be also based on something else (capacitance for example).
Ted