This is an option to tell lieAlgebra to consider the last weight of a generator as the homological degree.
The object LastWeightHomological is a symbol.
The source of this document is in /build/macaulay2-88fgJW/macaulay2-1.25.11+ds/M2/Macaulay2/packages/GradedLieAlgebras/doc.m2:797:0.