Soon; before long; someday — indicating a not-too-distant future without a fixed time.
忙しいけどそのうち遊びに行こう。
I'm busy now, but let's hang out sometime soon.
そのうち答えが分かるだろう。
You'll find out the answer before long.
そのうち時間ができたら手伝うよ。
I'll help you when I get some time one of these days.
Of the previously mentioned group; among them; referring to some or a certain number within that set.
応募者のそのうち三人が面接に来た。
Three of the applicants came to the interview.
提出された作品のうち、そのうち二点が入賞した。
Of the submitted works, two of them won a prize.
そのうちの何人かは賛成だった。
Some of them were in favor.