You can find better explanation than “The Meaning of Einstein’s Equation” (John Baez).

http://settheory.net/cosmology
http://settheory.net/general-relativity

– It is directly applied to an important example (universal expansion)
– The expression is simpler (relating 1 component of the energy tensor
to 3 components of the Riemann tensor)
– The relation between energy and curvature is not only expressed but
also justified
– Both (diagonal) space and time components of the relation are
expressed and justified, resulting in showing their similarity “like a
coincidence”.