Refers to a person who accompanies someone, often in a serving or supportive role. The word is somewhat literary or old-fashioned; in modern casual speech, 連れ or 仲間 are more common.
Compound of とも (companion) and ひと (person), with rendaku voicing of ひと to びと. The kanji 供 carries the meaning of 'attendant' or 'offer', reinforcing the serving nuance.