Complex sentence: The stabilization of the 7s electrons is called the inert pair effect, and the effect "tearing" the 7p subshell into stabilized and destabilized parts is called subshell splitting.
Split into simpler sentences: The stabilization of the 7s electrons is called the inert pair effect. The effects "tearing" the 7p subshell into the stable and unstable parts is called subshell splitting.