It is not possible to count stars but it is possible for astronomers to guess how many stars there are, though. They can use physics to create a good guess about how many stars there are in our galaxy. Then they can make a guess as regards to how many galaxies there are in the visible universe and finally multiply.
No. In our galaxy, the Milky Way, we have millions or billions of stars. The closest to Earth is the Sun. Outside of our galaxy are billions of other galaxies which contain billions of their own stars. The universe is larger than we can possibly imagine.