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Borrowing an example from Beezer's linear algebra text and modifying it slightly:

A = matrix(QQ, [[ 1, -3, 1],
                [-2,  1, 1],
                [ 1,  5, 1],
                [ 9, -4, 0]])
N = A.left_kernel()
v = N.basis()[0]
print v
type(v)

So you can access the basis, and if you're sure it's going to have just one element you can just get it as a vector. But in general a kernel is a vector space, so you can't just say "it" is a vector.