• 済すむ — to be settled, to end
• 済すます — to finish, to get through
• 救済きゅうさい — relief, aid
• 経済けいざい — economy
• 返済へんさい — repayment
• 弁済べんさい — indemnification

済 is closely related to resolving matters, whether financial, religious, or social. It appears in words like 経済 (economy) and 済度 (spiritual salvation), showing how "completion" or "helping through" is central to the character’s meaning.

仕事しごとが 無事ぶじに 済すみました。
The work finished safely.

返済へんさいは 来週らいしゅうまでに お願ねがいします。
Please repay it by next week.

This kanji has both on-yomi (サイ / セイ) and kun-yomi (すむ / すます). It appears frequently in daily life and economics. The kunyomi are often used in everyday conversations, while onyomi appear in compound nouns.