After successfully achieving level A2 you are a good tourist: you can ask questions, you understand the simpler answers, you can go shopping, you can ask for food and drink in the target language, you understand the signs, that is: you can manage.
After achieving level B1 you can look for a job and work among colleagues speaking the target language; you start understanding newspaper and radio news, TV programmes, you can even try going to the cinema or theatre.
After achieving level B2 you can start studies in the secondary schools and at the colleges and universities of the target language country. You have learned the structure of the target language and understood its logic – and by now you have surely got to like it. You start appreciating literature; you understand announcements at the railway station and what people are shouting in the street. That is you are starting to feel comfortable in the target language and in the target language country.
When you achieve level C1 you become an equal partner of the native speakers of the target language. You write, read and speak like they do, you can study, work and do research among them, you can continue expanding your knowledge of the culture, literature and history – that is the past and present of – the target language culture without difficulty.