What is the meaning of idiom or

You're asking about the meaning of the phrase "or". It's not an idiom, but a conjunction.

Here's what it means:

Or is used to connect two or more alternatives. It indicates that only one of the options is possible or that either one or both of the options are possible.

Examples:

* "Do you want coffee or tea?" (Only one choice is possible.)

* "We can go to the park or the beach." (Either option is possible.)

* "He is either happy or sad." (Only one emotion is possible.)

* "She likes to read books or watch movies." (She can enjoy both activities.)

Let me know if you have any other phrases you'd like to understand!