Waht does language Levels A1, A2, B1, C1 and C2 mean ?

The Commnon European Framework divides learners into three broad divisions which can be divided into six levels:

levels_enBasic Speaker
A1 Breakthrough or beginner
A2 Waystage or elementary

Independent Speaker
B1 Threshold or intermediate
B2 Vantage or upper intermediate

Proficient Speaker
C1 Effective Operational Proficiency or advanced
C2 Mastery or proficiency