What career can a master student take?
For a career in academia you basically need a doctorate. There are jobs for secondary school teachers and low level jobs at university. The secondary school positions are actually better than the low-level university positions, in most cases, however. Many places require additional certification for high school jobs, of course. 

Most people who earn an MS/MA either go on for more learning or head to industry/government where there are positions available. If you want to do research but without a doctorate, the best place is in some industry lab or (for CS) a software development company. The research will be pretty applied, however.