The Common European Framework of Reference for Languages, often referred to as CEFR, is an international standard for working out your ability within a language. It was established by the Council of Europe and aims to validate language ability.
The six levels within the CEFR are A1, A2, B1, B2, C1 and C2.
A full CEFR exam typically measures skills in listening, reading abilities, speaking and writing, That’s why some learners segment their abilities, for example stating that their listening in a language is at a B2 level but their speaking is only at a B1 level. Others just average out their abilities and say that they’re at a B1 level overall.