An idiom is an expression whose meaning cannot be predicted from the usual meanings of its constituent elements. It can have a literal meaning, but its alternate, figurative meaning must be understood metaphorically. Idioms come from spoken languages.
Idioms play a significant role in every language and may be defined as expressions peculiar to a language. They are basically fixed expressions. They are metaphorical rather than literal. The grammatical form of an idiom is invariable and fixed. The English language is full of idiomatic expressions. They are not a matter of logic and grammatical principles. They are set by long usage and their order of words should never be altered. They are mostly used when describing people, their appearance, character, mood, action or behavior. Many of them are also applicable to things or places. They are fun to learn and they make the language much more colourful.
Open somebody’s eyes to (Idiom) = Cause somebody to realize (Meaning)
Stand on one’s own feet (Idiom) = To be independent (Meaning)