The curtain falls on a quiet, domestic scene. Telegin plays the guitar, Mariya makes notes in one of her political pamphlets, Marina knits, and Sonya comforts her sad uncle Vanya.
Vanya was just on the verge of killing himself, by the way. He tried to steal some morphine to do the deed, but Sonya talked him out of it, asking him to wait until death comes naturally. Her final words, "We shall rest!" refer to their (natural) deaths.
Morbid, right?
Yeah, it is. The idea is that these people are wasting their lives, working to make others' lives easier and waiting to die. They don't have any rest or happiness in life, but rather than try to change things, they find it easier to just wait for death. And that's Chekhov's big criticism in this play. Wasted lives and mediocrity with no ambition are not on his good list.