Complex sentence: The term spacetime symmetries refers to various techniques that employ some form of symmetry to simplify problems and to find exact solutions of Einstein's field equations of general relativity.
Split into simpler sentences: The term spacetime symmetries refers to aspects of spacetime that can be described as exhibiting some form of symmetry. These symmetries are used to simplify problems and find ample application in the study of exact solutions of Einstein's field equations of general relativity.