Learning the language, at least at a basic level, is very impressive and a great way to secure business with Japanese companies. . Portuguese Portugues. Portuguese is a great language to learn as Brazil is becoming an economic superpower..Given that Spanish is the second most spoken language in America, it’s easily the best to learn for those looking to broaden their horizons within the USA. In addition to doing better business in the United States, Spanish could broaden horizons in countries like Paraguay and Ecuador..Arabic, Korean, Japanese and Chinese are often considered among the most challenging languages to learn for English speakers, and speakers of other European languages. Learning to read and write Chinese and Japanese is certainly challenging, and Chinese tones can be difficult to master..