There are several types of irony, but the one you're specifically referring to is likely verbal irony, where the speaker says something that is the opposite of what they actually mean.
Here are some examples:
* "What lovely weather we're having!" said sarcastically on a rainy day.
* "I'm so glad I lost my job, now I have all this free time!" said with a heavy sigh.
Other types of irony include:
* Situational irony: When the outcome of a situation is the opposite of what was expected.
* Dramatic irony: When the audience knows something that the characters in a story do not.
Let me know if you'd like to explore these other types of irony in more detail!