阳光 literally combines 阳 (yáng, 'sun' or 'yang' — the bright, active principle in Chinese philosophy) and 光 (guāng, 'light'), so it means 'sunlight' — the visible light and warmth emitted by the sun. It is a concrete noun referring to natural daylight, especially when clear and bright.

Figuratively, 阳光 frequently describes positive, open, healthy, or optimistic qualities — for example, someone with a 阳光的性格 ('sunny personality') is cheerful and approachable. This extended meaning reflects cultural associations of sunlight with vitality, clarity, and positivity. The word appears often in weather reports, health advice (e.g., 'get some sunlight for vitamin D'), environmental contexts, and emotional descriptions — making it versatile across literal and metaphorical usage.