One of the insights of the general theory of relativity has been to change our understanding of the relationship between gravity and spacetime. We now say that mass has the effect of distorting spacetime and it is that distortion that causes other objects with mass to move in ways that formerly we used to describe as being acted upon by a gravitational force that could act at a distance.
But visualizing that distortion of spacetime and its effects is not easy because the distortions are not visible in the three spatial dimensions that we can ‘see’ and must be described mathematically.
However, this video makes a valiant effort.
