Whenever there are two things, there is always the third, i.e. the relation between them. For example, light itself is an invisible form of matter, that if you were in space and a beam of light were passing in front of you, you would not see it unless the beam of photonic energy somehow hits something and reflects from that something to enter into your eyes, until then the beam of photons passing remains invisible. You could say, light itself is not really light as we know it, but when the photons of that energy physically hit the retina of an eye, the effect that it causes, and the way the brain interprets it, is what we know as light. A beam of light plus some reflective object in its path is equal to visibility.
Time is but the manifestation of all things in the physical world. Time itself has no singular or independent existence. Time is what we experience when we experience the physical world. Time is the way we experience the physical world. The physical world plus a human observer, the outcome, experience of time.
All things of the physical world change at a steady rate, not because some kind of stuff called time is passing through them because to change is the property of physical matter itself. When the earth goes around the sun, and turn upon its own axis, waters flow and seasons change, when trees grow and metals rust, when we see all this we say, time is passing. We manufacture devices to measure this rate of change, to keep track of a changing world changing all around us, to regulate our lives accordingly, and so the concept of time becomes just as real for us as running of the sand down the glass, as water going under bridges.
It seems to us everything is getting somewhere in time, flowing along in the river of time, and the universe processing something or itself. The fact is everything, the universe, IS going somewhere, but time is not taking anything anywhere, everything is getting somewhere by its own nature, the physical matter has to be in a certain state of flux to exist as matter, and time is the measure of that flux.