All you need to know:

Why PE need Original First Thunk(OFT)?

by Milad Kahsari Alhadi

From article:

Let me summarize a lot of things for you here. When you load a Library, for example, Milad.dll and then try to call a function from that like MPrint, dynamic loader of the windows operating system has to resolve the address of the MPrint function and then call it.