The word actionable has as its primary meaning "providing grounds for legal action", but in the world of management, it is the secondary meaning "capable of being acted upon" that is more common. Something that is actionable provides a specific demand for action. Although I'm not necessarily a big fan of the word itself, I definitely appreciate the value of the concept it is trying to capture.

Not Actionable Actionable
I'm thirsty. Can I get a glass of water?
This checkbox moved. Move it back.
Explain why you moved it.
Create a duplicate checkbox at the old location.
I'm seeing behavior X. Help me get behavior Y.
Explain why I'm getting X.

The concept is valuable because it emphasizes the importance of clear communication, and making sure people understand what you want. Without it, meetings turn into a passive-aggressive-athon, with people saying, "Oh, sorry, I didn't realize you wanted me to do anything about that. I thought you were just venting."

That's also why I'm not happy with the nounification of the word ask. It's not a requirement; it's not a demand. It's this vague ask thing. How do you prioritize an ask?