Anyway, the sign says:
× Smoothly and Speedy
◯ Smoothly and Speedily (better)
◯ Smooth and Speedy (best)When you want to use two words that describe something and connect them with a conjunction, they need to be of the same type.
- conjunction - 接続詞
The problem here is that "smoothly" is an adverb and "speedy" is an adjective. The hint here is that "ly" usually signifies an adverb, while "y" alone is usually an adjective.
I hope your holiday journeys are smooth and speedy.