As per title, what is like to be a Field Service Engineer, especially joining under fresh graduates program from,say energy sector company like GE, Siemen, Schneider Electric, Honeywell, Hitachi Energy? Will I be required to travel to sites often for work and possibly staying for long hours? What do you think of the career progression and salary? Could someone here enlighten me please? Much appreciated!

yes, as the name imply, "field" means that you need to frequently go to the client project office or location and communicating with external stakeholder, usually these field role will also include travel allowance

these reputable big name MNC usually have a good work life balance, if you OT, either OT allowance or extra PTO

salary should be good, btw are you looking to becoming one? I know a field engineer vacancy role in construction sector, europe MNC