Masiah, that is a good questions. Mechanical Engineering is the broadest field in engineering. There are many options for mechanical engineers. For me, I have done product development, project management, and people management in consumer electronics and medical devices. Mechanical Engineering work in HVAC (Heating, ventilation and air conditioning.) for sizing units and designing the ventilation systems as well as laying out the plumbing for the buildings. Some MEs go in to technical sales support. There are opportunities in doing Structural Analysis. Many MEs support manufacturing with the layout of the manufacturing floor, design of manufacturing equipment or test equipment. There are also opportunities in Reliability or Regulatory evaluations.
This really just barely scratches the surface. I hope this helps.