The meter that you have just done calls aerometer. This experiment, as well as others, demonstrates that the liquids have different densities. The density is defined as the mass of a substance by volume unit. In the present experiment, ordering the liquids by an increasing density we have: Oil, water, water with salt and honey. For the obtained results we can conclude that the oil contains less mass per volume unit than water, water with salt and honey.
The density difference verified between water with or without salt is easy to understand. When you add salt to water it was verified that the volume hasn't changed. On the other hand, in the addition end, the amount of mass contained in that volume is larger than the initial. In other words, the density of the water with salt will be higher than the one without salt. This because the water with salt contains more mass per unit of volume. It's easy or not?
In the particular case of honey, in the end of this experiment we can conclude that it contains the largest amount of mass per unit of volume. Therefore, it is heavier than the other analyzed liquids. Now, does the brown liquid, with carbon dioxide, that everyone knows, have higher or lower density compared water? Try it and you will know the answer!