What does "delovaya kolbasa" mean in Russian?
It is "delavaya kalbasa" literally
a busy sausage
The Wiktionary tells it's an ironic designation for a person who's always busy with something, who's demonstrably busy, the Web indicates that it could also be a businessman/woman.
While the answer provided is absolutely correct, it's not necessarily about somebody being pretentiously busy. "Деловая колбаса" can be applicable in many circumstances and is a rough equivalent of "you are such a clever/smart guy/ass" said ironically.
For instance, a daughter can suggest to her father to leave her all the candies in exchange for butter and her father can say: "Ну ты и деловая колбаса".