I have been playing for around eleven years. But I’m not as good as I could be since I rarely practiced for about 2/3 of that time.
I am learning Russian since my parents both learned it in school. I’m also improving my Japanese and French.
You can learn English, but it’s only for native speakers of another language. At least in the app, if you try to add another language, you will not be able to learn English. If you tap the “more” button underneath all the languages, there are options for native speakers of Arabic, Chinese, etc.