scale was a function in Base Julia up to version 0.4, before being deprecated in Julia 0.5 in favor of plain or broadcasted multiplication. This was the docstring in Julia 0.4:

scale(A, b)
scale(b, A)
Scale an array A by a scalar b, returning a new array.
If A is a matrix and b is a vector, then scale(A,b) scales each column i of A by b[i]
(similar to A*diagm(b)), while scale(b,A) scales each row i of A by b[i] (similar to
diagm(b)*A), returning a new array.