The pronunciation of “暖 b” is rather unconventional and not a standard term. However, if we were to break it down and try to pronounce it, “暖” in Chinese is pronounced as “nuǎn”. As for “b”, it is pronounced as “biː” in English. But this combination doesn't have a proper English pronunciation as it is an unusual and perhaps made-up or slang term. Without more context or a specific meaning assigned to “暖 b”, it's difficult to give a definite and proper English pronunciation.
