The CEFR (Common European Framework of Reference) describes what a learner is supposed to be able to do in reading, listening, speaking and writing at each level. These descriptors can apply to any of the languages spoken in Europe.
To enter level B2 you need to be a returning student or pass an assessment test.
Students in this level can understand the main ideas of complex text on both concrete and abstract topics, including technical discussions in his/her field of specialisation. Can interact with a degree of fluency and spontaneity that makes regular interaction with native speakers quite possible without strain for either party. Can produce clear, detailed text on a wide range of subjects and explain a viewpoint on a topical issue giving the advantages and disadvantages of various options.