When you learn any language, simply put Language: {name}. This skill represents how well you understand it. Level 5 is enough to get by politely, even if it's sometimes apparent that you're a tourist. At higher levels, you're familiar with slang, local idomata, and can reproduce all related accents. You're also familiar with the regal and poetic forms of that language if well-studied.
Language skills cannot be broken (as ten means completely fluency.) Speaking a related dialect (like how speaking Italian relates to Spanish or French) is -5 to your level.
Everyone has a natural language at Level 10, free of cost. Write it down if you like.