The symbol SPACE is used as notation for multiplication by scalars. The scalars are of type Number if the field is QQ, otherwise the scalars are of type RingElement.
i1 : M = lieAlgebra{a,b}
o1 = M
o1 : LieAlgebra
i2 : L = lieAlgebra{a,b}
o2 = L
o2 : LieAlgebra
i3 : f = map(L,M,{a,b})
o3 = f
o3 : LieAlgebraMap
i4 : describe(-2 f)
o4 = a => - 2 a
b => - 2 b
source => M
target => L