Question about the Kanji present in the title

Certain characters (referred to as counter words commonly) are read differently when used with numbers/other "quantifying characters" compared to their usual readings in compounds. Think of stuff like 一日, 一分, 一時 and similar. Same thing applies here. (quantifying characters aren't limited to numbers and include characters like 何, which is read as なん in these cases (何分, 何日, 何時, etc)

The title is correct in this context. The japanese writing system is a giant mess worse than english so this character can be read a bunch of different ways.

@Theo1899 I never claimed the title was incorrect, I was just wondering how it worked. Japanese really isn't a mess, it's just a language about as different from englsih as you can get.