Most people think that they speak one language, but this is not so.
There are more languages than ethnic languages – there are professional languages, the language of hobbies, sport, etc. The average person would not understand a medical conversation, nor a discussion between lawyers, but the same would be true of a football coaching session or a tennis coach or a chess grandmaster explaining strategy and moves. Simply put, every area of life has its own vocabulary that people need to learn in order to participate in conversation.
This shows that even the most undervalued person has great potential, and this should raise their self-esteem.
We are all multi-lingual, with great capacity for self-improvement.