It is hard to describe exactly what will be there. But there are some things we know.
Stars are sort of like a huge nuclear reactor, with a crazy amount of nuclear explosions and processes making them shine and shoot out energy. That also means that they all eventually run out of fuel. So if we wait long enough, well, all stars will die.
Our sun will do that in about 5 billion years.
At the same time, the universe is expanding, so things are getting farther and farther apart. However, this works at very large scales, so, for example, the gravitational attraction between our galaxy (the milky way) and the closest galaxy (Andromeda) is stronger than the expansion and thus both galaxies will collide at some point in the future, merging into one.
However, things will eventually be so far apart that the universe will be just dark, lonely and cold. But you know what? we are lucky we are here now because it is still long before that will happen and a lot of super cool things are happening all around us!