The Milky Way and Andromeda galaxy are on a collision course: in about 3 billion years from now the two galaxies will collide. Then over a span of 1 billion years or so after a very complex gravitational dance, they will merge to form an giant elliptical galaxy. That’s why the collision period is aproximated to a period from 3 to 5 billion years from now.
Our galaxy, the Milky Way, is a collection of about 400 billions stars spread out in a thin disk more than 100,000 light year across. Our Sun, the center of the solar system, is one of those stars sitting about midway out in the disk moving around with the others on nearly circular orbits. The Milky Way would look like one of the most spiral galaxies if we could see it from the outside – nothing special.