English: “But these are those from which you shall not eat” — this teaches that the unclean birds are enumerated in detail while the clean ones are stated in general; any bird that possesses the signs of purity is permitted.
On the daf / in context: The Torah lists the forbidden birds by name and leaves the permitted ones under the general rule of “every clean bird.” The presence of the classic signs of a clean bird therefore permits it.
Type of Learning
Derash on the structure of the list (Sifrei / Chullin) — specific prohibition versus general permission.
What Is Learned
Unclean birds are identified by explicit names; any bird not listed and possessing the signs of purity may be eaten.