Light can act as both a wave, and as a particle. This is known as ‘wave-particle duality’, and was something that was discovered by Einstein amongst others, so you’re in pretty good company in asking this question!
When it is thought of as a particle, it is like a packet of light with a specific energy. It’s a bit like the work that I’m doing, where packets of specific energy can drive my water splitting reaction.
It has also been shown to act as a wave though, as if you try and squeeze light through a small gap, the waves that come out of the other side are curved, and so have been diffracted. Here’s a picture to explain that better:
So light is therefore both a wave, and a particle! Hope that answers your question Umut, but if you want more information, give me a shout, and we can talk about it.
Mike, don’t worry. No one understands quantim mechanics. It was my worst Uni module!