Decide whether a DFA accepts the empty language
Re-read your textbook chapter on DFAs and NFAs -- you'll find everything you need to know there.

See also the following questions, which both have answers to your question embedded in their answers (make sure to read carefully):


Can a Turing machine decide the language $L_\emptyset$ of machines with empty language?
Undecidable among these for turing machine


Next time, tell us what you have tried, to solve the exercise on your own.