noun
one flower; a single flower
Literal meaning: exactly one flower, often used in counting or describing a single bloom.
花瓶に一花だけ活けてある。
There is just one flower arranged in the vase.
noun, noun which may take the genitive case particle 'no'
success; prosperity; a moment of glory
Figurative use, often in the phrase 一花咲かせる (to achieve a brief success or enjoy a moment of glory). Implies a single, notable achievement or flourishing period.
彼は若い頃に一花咲かせた。
He had his moment of glory when he was young.
定年後に一花咲かせたいと思っている。
I want to achieve something notable after retirement.
Compound of 一 (one) and 花 (flower). The figurative sense likely derives from the image of a single flower blooming, symbolizing a brief but notable success.