Can you give few examples regarding what IE’s do actually?

There are a lot of examples; few of them are given below which will give you basic idea of what IE’s actually do:
• Reconfigure airport check services to shorten lines and make passengers happier
• Design a more efficient car assembly line to save on manufacturing costs
• Streamline an operating room so that is safer, faster and easier to use
• Determine the fastest way to transport perishable goods cross-country, even during bad weather.