In physics, it is assumed that all processes of nature take place in a four-dimensional spacetime. In this spacetime it is possible to measure lengths in all directions, e.g. in the time direction. As a consequence of relativity theory, what is measured by one observer as a length in the time dimension, will by another observer be measured as a length in both time and space, if that second observer is moving relatively to the first observer.
So time itself is a dimension of spacetime, not something that is described as a quantity that moves in some other space. Although I wouldn't be surprised myself if in the future it turns out that time and space must be described in a different manner than it is today in order for physics to explain the world around us.