This is an option to tell lieAlgebra to assign the given "signs" to the generators, which are either 0 (even) or 1 (odd).
The source of this document is in /build/macaulay2-88fgJW/macaulay2-1.25.11+ds/M2/Macaulay2/packages/GradedLieAlgebras/doc.m2:754:0.