The neutral kaon may be a particle or an antiparticle... whether it is a particle or an antiparticle may be considered a state of the system consisting of a single neutral kaon. It's something you can measure.
In QM terms, you can imagine an operator that measures the particle-antiparticle state of the neutral kaon ... the trouble with any of us going further is that "finding out about the neutral kaon oscillations" is the task you have been set. If we just tell you, that would amount to "doing your homework for you" which would defeat the purpose of assigning you the work in the first place. There is a great benefit to you in learning to carry out this sort of research without knowing initially where to start or what you will discover. Indeed: only if you are willing to search into the unknown can you be a scientist. Go for it!
Have you followed advise received so far and looked at the wikipedia page or searched your college library for information?
If you do not follow advise, we cannot help you.