Time has two attributes. It has duration and direction.
Time’s duration can be explained in terms of the speed of light. The fact that there’s a speed limit that applies to all things means that all transfers of energy from one object to another is limited in how fast they can be made. The bigger a thing is, the harder it is to change its energy. Inertia is in this way a consequence of the speed of light and the limit this sets on how fast energy can be transferred from one object to another. Our subjective experience of time is therefore relative speeds. Time is the duration of one thing relative to another.
Time’s direction is another matter. It has to do with the direction that energy flows. The past is where energy was before an event. The future is where energy will be after the event. Now is the state of the world in the present, which is defined in its entirety by energetic particles and their pilot waves.
Since everything in the universe, including our consciousness, is driven forward by energy moving from one object to another, our notion of time is that of perpetual forward motion.