This are presets for JOSM that just provides word lists for frequently used keys and values (by me). If the list is included as a preset in addition to the standard presets, these keys and values can be autocompleted while entering them into JOSM, which is faster and prevents spelling errors.
See https://josm.openstreetmap.de/wiki/TaggingPresets for information about how Presets in JOSM are working.