In fact, the dialect of Guiliu (Guilin, Liuzhou) in Guangxi is quite similar to Mandarin. Foreigners can generally understand it. The pronunciation of "hello" in Guilin dialect in Putonghua is probably "tired", and the mouth shape of that "tired" is like "O". But some Guilin people can't tell the initials "n" from "l", "f" and "h", so you can.