Day starts, birds sing out.

Meaning: This sentence describes the early morning, when the sun has risen and birds are singing to greet the new day.

Choice of Words: Day means the period between sunrise and sunset, and starts means begins. Birds are animals with feathers and wings, and sing out means to make a sound with their voices. When you put them together, "Day starts, birds sing out" means the new day begins, and birds start singing.