* Warm-up is a noun, referring to a period of preparation.
* In is a preposition, indicating location or position.
* Stage is a noun, referring to the platform where a performance takes place.
The phrase is likely a shortened form of "warm-up on stage," where "on" is the preposition.
Here's why it's important to understand this:
* Grammar: Understanding parts of speech helps you write and speak grammatically correct sentences.
* Meaning: The choice of preposition can slightly change the meaning. "Warm-up in stage" sounds strange, while "warm-up on stage" is clear and understandable.