Getter and Setter are the newer version of BlueprintGetter and BlueprintSetter that's meant to be supported more widely, currently it should work with details panels, blueprints and sequencer but won't do anything with C++ or if someone directly modifies the property with ContainerPtrToValuePtr. If you don't specify a function name for Getter and Setter it will look for functions called Get and Set respectively
From @MrHibbitts and @Ben on Unreal Slackers: