Do you communicate with different people using different languages? You might have a bilingual family, or have contacts in America, Japan, and Germany and interact with them in their respective country's languages.
When you go to email those contacts, how do you switch between languages? If Gmail is your email client of choice, the task is actually far easier than you think.
And given that Gmail supports a very wide range of languages, the chances are good that whatever you need is available. Given that Gmail supports everything from Afrikaans to Zulu, it's highly unlikely there's a language that's not there (although, sadly, you won't find Klingon available