そのうち
そのうち · sonouchi · JLPT N3 · expression
before long
⏳ その + うち = that + within: within that stretch of time, it will happen
その means that and うち means inside or within, so そのうち is literally within that, meaning somewhere inside the time ahead. It is vague on purpose: something will happen eventually, but no date is set. Example: そのうち分かる means you will understand sooner or later.