Spanish,Portuguese and Mandarin. I'd say close to like half the world's population speaks one of these three languages. 90% of people in China are Han Chinese so out of 1.5 billion ppl you can basically talk to 1.35 billion of them and they'll most likely understand you(unless they're Shanghainese). Spanish and Portuguese cover basically all of Latin America, Spain, Mexico, Portugal and the Philippines, so you're good.