Time is directional, because time depends on things and the development of things is directional, so time is also directional. But this direction is not necessarily one-way, it may be reversible, that is, we may go back to the past. Of course, it is more likely to go to the future. The direction in mathematics, if only considered from algebra, belongs to the quantitative relationship, that is, 1, 2, 3 and so on. If only from the geometric point of view, its directivity belongs to the spatial form. For vectors, it may include "quantitative relation" and "spatial form".

Note: The above views are purely personal and should be adopted with caution.