It is a self-diagnostic test that has been made along the CEFR (Sefaru), which is a criteria that have been internationally trust.
When you press the level diagnostic test, because the question that is in accordance with the level comes out, YES, please answer NO. It does not matter when you start from a level above those who are confident in English.
B2 is the minimum language requirement that the UK government is considering making compulsory in granting work visas for foreigners assigned to the UK offices of overseas companies. According to a Japanese survey sponsored by the Japanese Ministry of Education, Culture, Sports, Science and Technology, most people working in an Anglophone environment felt at least a B2 level was necessary, and that C1 was desirable in conducting business.