What is meant by your statement: "Then you say and the razor passes over it"? And does the ruling on underarm hair differ from that on pubic hair? What do you advise those who teach children who are nearing puberty or have already reached it, regarding the rulings of puberty?

The phrase "the razor runs over it" means that coarse hair deserves to be removed with a razor, and that the growth of armpit hair is not a sign of puberty. Matters related to worship should be clarified for children with politeness and modesty, using euphemisms, following the example of the Quran and Sunnah (definition).