It depends… some projects are very specific, one-off things for one customer (ie, company X needs to check if a piece of equipments works, so they send it to us and we measure it against a realllly accurate standard, job done, not much impact on humanity), but other things I do develop new technology (a new type of equipment, or a new measurement technique using a laser that no one has thought of before) and that has the potential to be used in the future by lots of companies, which may have a major impact, but maybe not for 10 years. So it all depends! No one saves the world every day, but we all do our little bits to make things better.
Myself, I work in the RF generator plant of a particle accelerator – think of it like the engine on a ship. The work I do allows other engineers and scientists to do amazing things, from investigating how proteins work to design new medicines, to reading ancient books without opening them; they can look at the microscopic cracks inside the wing of an aeroplane to work out how to make them stronger and lighter, or watch how computer memory chips work to design faster, smaller, devices than ever before.
If I work in the engine of the ship, then those other people are the explorers who travel on board. They wouldn’t get far if the engine didn’t run!