分 has a second reading 分 meaning 'part / share / ingredient' — the share-noun sense. The verb 'to divide' and the measure-uses (minute, point, cent) are always fēn; words like 身份, 缘分, 安分, 过分 take fèn.
grammar
分钟 is 'minute' as a duration: 等我五分钟 'wait five minutes'. Bare 分 gives clock time: 八点十分 '8:10'.
Top two strokes — 八 here is NOT the number 'eight' but its original pictographic meaning: two strokes pulling apart, depicting division. The number 'eight' is itself a phonetic loan onto this divide-image. The opening at the top of 分 visually pulls outward, supplying the meaning of separation.