If you want to know your level of grammar, vocabulary and written and oral comprehension, EF English Live offers a free online English test that covers these subjects, the EF SET. It is designed to assess your level of English according to the Common European Framework of Reference for Languages (CEFR).
The EF SET will give you a score that corresponds to one of the six levels of proficiency in English defined by the CEFR, ranging from elementary (A1) to advanced (C2). By knowing your level, you can choose English courses that are adapted to your level of proficiency and therefore progress more quickly.
It's important to remember that regular practice is the key to improving your English. As well as taking courses, you can also listen to radio programmes and podcasts in English, watch films and series in their original version, and read books in English. The more you practise, the more comfortable you'll become with the language and the faster you'll progress.
In short, knowing your level of English will help you assess your skills and choose the most suitable English courses.