There are a lot of idioms in English originated from different English speaking countries all over the world and there seems to be an infinite list. No honestly! Even native speakers are constantly learning new ones all the time. Just because you have never heard of it or use it, it doesn’t mean it doesn’t exist.
Idioms make a language more interesting and melodic. It turns simple words into a story and delivers a new message. Take ‘give the benefit of the doubt’ for example, at pre-intermediate level, these vocabularies shouldn’t be difficult and most students would understand what each word means. But when they are put together, it means: to believe something good about someone, rather than something bad, when you have the possibility of doing either (by The Free Dictionary, see citation below)
See the idiom in an example: People tell me I shouldn’t trust him, but I’m willing to give Simon the benefit of the doubt and wait and see what he actually offers.
Here’s a rough translation to Spanish: concederle a alguien el beneficio de la duda
The best way to learn idioms is to watch movies and series because while you might not know the exact meaning behind the phrase, the story often gives it away and you can guess what it means! Keep a list of new vocabularies with you and after the film, google it or ask a teacher.
Who said having a movie marathon or watching an entire season of The Walking Dead was a waste of time?
give the benefit of the doubt. (n.d.) Cambridge Dictionary of American Idioms. (2006).