This is the 5986th most frequent Russian word.
сияние
Radiance or shining.
In this sentence, 'сияние' refers to the metaphorical radiance that joy brings to someone's expression.
Ее лицо осветило яркое сияние радости.
Her face was illuminated by a bright radiance of joy.
Here, 'сияние' describes the literal radiance or glow emitted by the moon.
Сияние луны пробивалось сквозь густые облака.
The moon's radiance broke through the dense clouds.
In this example, 'сияние' refers to the gentle, glowing light emitted by the Christmas tree lights.