What is meant by "molecules occupy no volume" in the ideal gas law?? Very confused?

This is a valid umption at low pressure. In that case the space around each molecule is much larger than the volume of the molecule and we can ume that adding more molecules does not decrease the volume available for other molecules and even that the molecules do not "see" each other. If the density increases, the molecules can start to interact with each other -- and the gas starts to deviate from the ideal law.