The kanji 健 primarily conveys the idea of "healthy," "strong," or "vigorous." It implies physical and mental well-being, indicating a state of being free from illness and possessing strength and vitality. The meaning encompasses both the state of health and the act of being healthy.

・On-yomi (音読み): ケン (ken) ・Kun-yomi (訓読み): すこやか (sukoyaka)

⚫︎健康 (けんこう) Translation: Health; healthy; wellness. ⚫︎健康診断 (けんこうしんだん) Translation: Health checkup. ⚫︎健脚 (けんきゃく) Translation: Strong legs; good walker.

I am sorry, but I do not have enough reliable information to provide an explanation of the correspondence between 健 and Vietnamese.

The kanji 健 is a phono-semantic compound (形声文字). It is composed of two parts: a radical and a phonetic component. The radical is "人" (person/human), which provides the semantic component. The phonetic component is "建" (ken, to build/construct), which provides the sound of the kanji. Originally, the character's meaning was related to building, which later evolved to include the meaning of being strong and healthy, much like a well-built structure.