It’s a fifteen minute walk from here to the station.
That onion is the queen's portion.
Do you know what a blowfish would do if you tickled it for seven minutes?
This word has two meanings, both of which you learned with the kanji: minute and part or portion.
This word is almost always attached to something, which is probably why this single kanji vocab word uses the on'yomi reading instead of the kun'yomi one. If you know the kanji reading, you know this vocab's reading as well, but the reading is different depending on the meaning:
If it means minute, it's read ふん. However, due to rendaku, it is also read as ぷん after certain numbers.
If it means part or portion, it's read ぶん. Probably because your buns come in two parts. Ohoho.