Roadworks are repairs or building work happening on a road: a new surface, holes, pipes under the street, cones, slow traffic. British signs say roadworks ahead. The word is nearly always plural, even for one job, and it often takes are: the roadworks are going on for weeks. American English more often says road work, or just construction. Though actually, it does not tell you how big the job is — one lane or a long stretch — only that the road is being worked on and you should expect delays. It is a practical public word, not a fancy one.