If you have passed the proficiency test of a certain language or obtained relevant certificates, you can directly fill in the name and score of the certificate, such as CET-6 550, Putonghua 92 and Japanese N2 180.
If you haven't taken the language proficiency test or have no relevant certificates, but you have certain listening, speaking, reading and writing skills in a certain language, you can describe your level in the following words, such as: proficient in English and able to communicate fluently; General Japanese, able to communicate simply; Standard putonghua, clear pronunciation, etc.
If you have only a preliminary understanding of a language, or are in the process of learning, you can use the following words to describe your level, such as: english introduction is learning; Basic Japanese, master common vocabulary and sentence patterns; Good mandarin, a little accent, etc.