in the context of reversing a packed binary, what does VA and OEP means? and How can IAT be fixed manually?
VA = virtual address. See VA (Virtual Address) & RVA (Relative Virtual Address)
OEP = original entry point. See Unpacking binaries in a generic way
How does IAT be fixed manually?
This question was asked and answered here: How would I go about rebuilding the IAT of a packed executable?
Have a look at Scylla as well.