leann is ale, for instance leann dubh is stout, but to throw a spanner in the works, leann úll is cider, and leann piorraí is perry! In legislation it is used to mean beer generally, as in "ceadúnas mionreacaire leanna" which is a beer retailer's licence.
Folláin means wholesome, in the sense of healthy and fulsome. All of my knowledge has been scavenged from focal.ie which is a database of official irish translations, mostly from various legislation and other government documents.