Modifier + 部分 + 的 + Noun
The noun 部分 (bùfen) means "part," "section," or "portion" in Chinese. It is used to refer to a subset of a larger whole. It commonly appears with modifiers like 大 (large) or 小 (small) to indicate the relative size of the portion.
这本书的第一部分最有意思。
Zhè běn shū de dì yī bùfen zuì yǒu yìsi.
The first part of this book is the most interesting.
大部分同学都通过了考试。
Dà bùfen tóngxué dōu tōngguò le kǎoshì.
Most of the classmates passed the exam.
工资的一小部分用来交房租。
Gōngzī de yì xiǎo bùfen yòng lái jiāo fángzū.
A small portion of the salary is used to pay rent.