Pittsburg

not a lot but enough

There's not a lot of people but enough to make it fun.

When 'not a lot but enough' people do something it means the number of people doing something isn't big, but the ones that do it have an impact.  According to the example, there is an acceptable number of people living in Pittsburgh to make it a fun and interesting city. Notice the following:

1. He doesn't have a lot of friends, but enough to keep him busy.
   
2. We don't have a lot of sugar, but enough for the recipe.
   

main campus

Oakland is where Pittsburgh University main campus is.

The 'main campus' is the central campus or where most of the classes and offices are. Notice the following:

1. They have very good transportation to the main campus.
   
2. All of my classes are on the main campus this semester.
   

hang out

There are lots of college kids around, and it's fun to hang out.

When you 'hang out' in a place you casually spend time there for your own enjoyment. Notice the following:

1. This is a really nice room to hang out and read.
   
2. He hangs out watching television most of the time.
   

rival universities

Are University of Pittsburgh and Penn State rival universities?

Universities that compete with the University of Pittsburgh in sports or academics are its 'rivals' or 'competitors.' Notice the following:

1. Having rival universities make competition fun and exciting.
   
2. We are playing one of our rival universities in football this weekend.
   

boring

The fact that it's quiet makes it boring.

If something is not fun or interesting then it is 'boring.' Notice the following:

1. The guy I went on a date with last night was extremely boring.
   
2. The previews looked good, but the movie was really boring.