就此 (jiù cǐ) is an adverb meaning 'at this point' or 'thus,' used to indicate that something happens immediately after or as a consequence of what was just stated. It is similar to 于是 (yú shì) but is more focused on the specific moment or point in discussion, while 于是 is a conjunction linking clauses. Unlike 从此 (cóng cǐ 'from then on'), 就此 points to a single moment rather than a new ongoing state.