visa vs countenance

visa and countenance both are nouns.

Word	Noun	Adjective	Verb	Adverb
visa	Yes	No	Yes	No
countenance	Yes	No	Yes	No

As nouns, countenance is a hypernym of visa; that is, countenance is a word with a broader meaning than visa:

visa: an endorsement made in a passport that allows the bearer to enter the country issuing it
countenance: formal and explicit approval

Other hypernyms of visa include endorsement, imprimatur, indorsement, sanction, warrant.

visa (noun)	countenance (noun)
an endorsement made in a passport that allows the bearer to enter the country issuing it	the appearance conveyed by a person's face
	the human face (`kisser' and `smiler' and `mug' are informal terms for `face' and `phiz' is British)
	formal and explicit approval

visa (verb)	countenance (verb)
provide (a passport) with a visa	consent to, give permission; permit
approve officially