A grammatical element meaning 'to the extent of' or 'just as much as'; attached after a noun or clause to mean 'the amount/degree that ...' or 'as much as ...'.
働いた分だけ給料が増えるのは公正だ。
It's fair that pay increases in proportion to how much you work.
期待した分だけ失望も大きかった。
The disappointment was as great as the expectations.
時間が長い分だけ注意が必要だ。
The longer the time, the more caution is needed.
努力した分だけ成果が出ると信じている。
I believe results come in proportion to the effort put in.