Russian cases are tough 😫 and what makes them even tougher.... is when they're partly invisible! I have lots of photos on this topic, so let's start with this one.
Decoding a Russian phrase
aka the thought process of a language learner
This cup (which contained a smoothie) simply reads "an orange mood". But wait - it's not in the nominative form оранжевое настроение. It's clearly in some other case*. Why? 🤔 It must be part of a longer phrase. And the first part must be merely implied, probably something really obvious to native speakers.
*the genitive case
Luckily this one isn't too difficult once you've heard the ubiquitous хорошего дня! that every cashier says 100 times a day. Because they say it 100 times a day, they drop the first part: желаю вам хорошего дня, I wish you a nice day. All that's left is хорошего дня, which is in the genitive case.
We have the same kind of ellipsis in English. I hope you have a nice day becomes Have a nice day. Things are a little simpler here since English isn't case heavy like Russian is.
Anyway, seeing two lonely words in the genitive case was a big clue that the missing part of the phrase was probably something like желаем вам. Желаем вам оранжевого настроения, We wish you an orange mood.
The problem now is simply a vocab one. What exactly is an orange mood? 😅 I don't exactly know. I asked a couple of friends. They couldn't say it was really a specific thing, but it probably implied a cheerful and positive mood.