If this is tripping you up I'm guessing you are at the start of your jp journey. Just know that this is the type of thing that you will iron out pretty quickly once you learn more nouns that use 分, since 90+% of them are read ぶん or ふん, especially when 分 is the 2nd kanji. わ is the standard kunyomi (comes from jp) reading and you tend to encounter it in verbs. ぶん-ふん are the onyomi (comes from ch). Some people find it helpful to devote some time to kunyomi-onyomi study, but personally I've just stuck to learning words and gaining the intuition for readings as my vocab increases.
Just know that this is the type of thing that you will iron out pretty quickly once you learn more nouns that use 分, since 90+% of them are read ぶん or ふん, especially when 分 is the 2nd kanji.
わ is the standard kunyomi (comes from jp) reading and you tend to encounter it in verbs.
ぶん-ふん are the onyomi (comes from ch).
Some people find it helpful to devote some time to kunyomi-onyomi study, but personally I've just stuck to learning words and gaining the intuition for readings as my vocab increases.