Don't hike very close to the border with Azerbaijan without checking first with villagers about safety. Most tourists will never get close to the border, but if you plan to, then find out what you need to know first.
talk
Aside from the universally spoken Eastern Armenian, Russian is almost universally spoken. English, French and German are languages that many have studied in school, but few have had a chance to practice. The youth are your best bet for English proficiency. Most signs are in Armenian and often in English and Russian as well.