"Hebrew, Hungarian, and Vietnamese" sounds like the setup for a rather tasteless "guys walk into a bar" joke. But don't worry, readers of delicate disposition: it's just the latest update to DuoLingo, the much-loved language learning app. The August 1st update posted to the Play Store lists all three languages as additions to its growing list, so feel free to bone up on them if you're planning an oddly specific bit of international travel.
Hungarian and Vietnamese speakers can also use DuoLingo to learn English. Oddly, Hebrew-to-English isn't available as an option in the tool. According to Wikipedia Israel already has 85% English proficiency (and Hungary and Israel only have about 10% of the population of Vietnam anyway), so maybe it's a priority decision on DuoLingo's part.
DuoLingo's game-like approach to linguistic learning has earned it fans all over the world. The latest expansion means that there are no less than 19 courses for English speakers, with many more available for courses into English and across other languages, all for free. And if that's not enough to get you to try out the service, they're going to add "Klingon for English speakers" at the end of this year. K'plah!