永 (yǒng): Forever, eternal, perpetual. This sets the timescale for the blessing: eternity.
结 (jié): To tie, to bind, to form a knot. This character provides the powerful imagery of two things being securely fastened together, like the traditional Chinese “concentric knot” (同心结, tóngxīn jié), which symbolizes love.
同 (tóng): Same, together, with. This signifies unity and a shared nature.
心 (xīn): Heart, mind, or core. In Chinese culture, the heart is the seat of both emotion and thought.
When combined, 永结同心 (yǒng jié tóng xīn) literally means “Eternally Tie the Same Heart.” The characters create a beautiful mental image of two individual hearts being permanently bound into a single, unified entity, destined to beat as one for all time.