This equation computes the Vector Norm, the positive length of a vector, of the four-vector , `vec"Vec"`.
There all kinds of vectors applied in physics for forces, positions, velocities, acceleration, etc. The position vector, often represented by `vecr` can be decomposed into its three components parallel to the Euclidean three-space axes: `vecr = r_xrhati + r_yhatj + r_zhatk`.
Similarly, a velocity vector could be decomposed into its three Euclidean components as: `vecv = v_xrhati + v_yhatj + v_zhatk`
Then spacetime has four component, as do numerous other physics elements, so that `vec"Vec" = "Vec"_1hatu + "Vec"_2hatv + "Vec"_3hatw + "Vec"_4hatx`
This equation computes the norm of a 4-vector. The 4-vector does not have to represent some geometric and/or time representation of space. It can represent many different conceptual elements that have 4 components that comply with the general rules for vector mathematics.