This 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 under different conditions. 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 quite some depth by showing and explaining some of the experiments. It tells you a bit 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!
If you have any questions, leave them below and until next time, take care.