Dramas and TV shows are a great way to study English!

The key is, watch a drama that is made BY native speakers FOR native speakers. You will hear more natural English, casual vocabulary and phrases, and real life pronunciation! "Textbook" English is not always the same as "real life" English!

For beginners, I recommend watching shows for younger children. The storyline is easy to understand so you can focus more on new phrases, grammar, and listening. Some great ones are Disney or Pixar movies, or shows like Sesame Street.

For intermediate students, try comedies or "sitcoms". Comedy is very difficult to translate, so you need to understand ALL aspects of English. For comedy, try something like Friends or How I Met Your Mother. 

For advanced students, try medical dramas or crime shows. They have more advanced vocabulary and speak quickly! For medical dramas you can try ER or The Good Doctor. For crime shows you can try Law and Order or NCIS or FBI!