This my friends is one of the biggest questions in Physics and does not have a definitive answer. What us physicists CAN do is explain theories to attempt to answer this question and even set up experiments to show how light behaves. It is proven that light exhibits both particle like behaviour and wave like behaviour but it depends on the setup of the experiment so what can it actually be?
This video goes into more depth showing and explaining some of the experiments, talking about the history of answering this question and helps you better understand how physicists think about this topic. If it confuses you more, chances are the video is answering the question well!
Any questions feel free to ask below and I will be happy to respond. Mystifact