English in Brazil by Carina Fragozo is a very popular place online for Brazilians who are trying to improve their English. She has a YouTube channel – where there are hundreds of videos (mostly 10-15 minutes long, in Portuguese). These explain English grammar, pronunciation, and vocabulary, and also offer encouragement and general study tips.
There are videos about many different topics for people with some English experience – such as this one about silent letters (letters that aren’t pronounced) in English words. But there are also videos with “survival English” for beginners – like this one about shopping in a supermarket.