[GianFabien]

That was a very nasty comment. Whoever said it to you, probably wasn't multilingual.

I have worked on a large system for a multi-national drug manufacturer. Some modules were written by Spanish speakers, others by Germans, a few by French and about half by English speakers. It worked well. The only real problem was that variables and function names were all in their respective native languages. At least the module names were all in English (well sort of). I ended up maintaining it because I spoke all those languages (badly) and was willing to use various dictionaries. It was an experience!

In my experience the vast majority of books and internet resources are in English as are the keywords in most programming languages. If you can read English at high school level you should be Ok.

Since programming relies on teamwork, you need to speak the local language well wherever you live and work.