according to the Common European Framework of Reference Levels:
A0 – absolute beginner
You are a complete beginner or have very little knowledge of the foreign language
A1 - elementary
You can understand and use familiar everyday expressions and very basic phrases aimed at the satisfaction of needs of a concrete type. You can introduce yourself and others and you can ask and answer questions about personal details such as where you live, people you know and things you have. You can interact in a simple way provided the other person talks slowly and clearly and is prepared to help.
A2 - lower intermediate
You can understand sentences and frequently used expressions related to areas of most immediate relevance (e.g. very basic personal and family information, shopping, local geography, employment). You can communicate in simple and routine tasks requiring a simple and direct exchange of information on familiar and routine matters. You can describe in simple terms aspects of your background, immediate environment and matters in areas of immediate basic need.
B1 - intermediate
You can understand the main points of clear standard input on familiar matters regularly encountered in work, school, leisure, etc. You can deal with most situations likely to arise whilst travelling in an area where the language is spoken. You can produce simple connected text on topics that are familiar or of personal interest. You can describe experiences and events, dreams, hopes and ambitions and briefly give reasons and explanations for opinions and plans.
B2 - upper intermediate
You can understand the main ideas of complex texts on both concrete and abstract topics, including technical discussions in your field of specialisation. You can interact with a degree of fluency and spontaneity that makes regular interaction with native speakers quite possible without strain for either party. You can produce clear, detailed texts on a wide range of subjects and explain a viewpoint on a topical issue giving the advantages and disadvantages of various options.
C1 - advanced
You can understand a wide range of demanding, longer texts, and recognise implicit meaning. You can express yourself fluently and spontaneously without much obvious searching for expressions. You can use language flexibly and effectively for social, academic and professional purposes. You can produce clear, well-structured, detailed text on complex subjects, showing controlled use of organisational patterns, connectors and cohesive devices.
C2 – mastery
You can understand with ease virtually everything heard or read. You can summarise information from different spoken and written sources, reconstructing arguments and accounts in a coherent presentation. You can express yourself spontaneously, very fluently and precisely, differentiating finer shades of meaning even in the most complex situations.