Portion, Section, Part
noun
Part of a part? That's a portion, a section of that part, and even a part in itself!
ぶぶん
This is a jukugo word, which usually means on'yomi readings from the kanji. As long as you know the readings for these kanji, you should be able to read this word just fine.
この部分を見て下さい。
Please take a look at this part.
台風の影響で、水道の一部分が止まっています。
A part of the water supply has stopped due to the typhoon.
ビデオのこの一部分だけ使ってもいいですか？
Is it okay to use this one section from the video?