After a long, gray winter, it's hard to remember what a bright, sunny day is like. Bright means shining with light.
The adjective bright is good for describing anything that emits, reflects, or is full of light — like the bright moon, the bright sky or the bright, well-lit room. Bright can also mean vivid or vibrant — such as a bright purple three-piece suit. More figuratively, bright means "full of hope or possibility" — like your bright future as a marine biologist.