It’s a kind of slang or dialect speech from a stereotype of people in rural areas(hillbilly, redneck, or just country), also as gold prospectors(1840’s) are commonly portrayed in films.

“Them there hills”, which means, “those hills over there”.

Them/their are pronouns for non-binary people replacing the gendered he/his or she/hers.

It is a pun and an excellent one at that.