Learn French: Le public va applaudir la pièce dans quelques secondes. - The audience is going to applaud the play in a few seconds.

When talking about the future, dans followed by a time expression means in a certain amount of time from now. So, dans quelques secondes means the clapping will happen a few seconds from this very moment. You would use en to say how long an action takes to complete, rather than when it will start.

Doesn't la pièce usually mean a room or a coin?

Yes, pièce is a very versatile word! While it often means a room or a coin, in the context of an audience (le public) or a theater, it means a play. This is actually short for une pièce de théâtre.

Why is the verb singular (va) when an audience is made up of many people?

Even though le public represents a large group of people, it is grammatically a singular noun. You treat it as a single unit, so you use the singular il (he/it) form of the verb aller, which is va.

How do we use the word quelques?

Quelques translates to a few or some. It is a plural word, which is why the noun that follows it must also be plural, like secondes. You use it when you want to express a small, unspecific number of things.