"I always go to work by bus."
Translation:Yo siempre voy al trabajo en autobús.
Yes. Trabajo can be either a verb or a noun. As a noun, it does mean a job, place of work, or a jobs general ("buscar trabajo," to look for work).
English has a lot of such words ("I escort you" vs. "I am your escort" etc). I suppose in Spanish, as in English, it's simply a matter of learning each one individually.