The statement of the more general "Chebotarev theorem" is in terms of the Frobenius element of a prime (ideal), which is in fact an associated conjugacy class "C" of elements of the Galois group "G". If we fix "C" then the theorem says that asymptotically a proportion |"C"|/|"G"| of primes have associated Frobenius element as "C". When "G" is abelian the classes of course each have size 1. For the case of a non-abelian group of order 6 they have size 1, 2 and 3, and there are correspondingly (for example) 50% of primes "p" that have an order 2 element as their Frobenius. So these primes have residue degree 2, so they split into exactly three prime ideals in a degree 6 extension of "Q" with it as Galois group.