Is a splice a coupler, like a female slip coupler?

Is a stub, just a cut out piece of a pvc pipe?

Is MIPT/FIPT two types of NPT. Or is NPT a different type of thread?

I'm just trying to understand some of the terminology used in pluming.

"Is a splice a coupler, like a female slip coupler?"
When you splice two pipes together you use a coupling to do it.

"Is a stub, just a cut out piece of a pvc pipe?"
A stub-out is any pipe sticking out of the wall to pick up a fixture.

"Is MIPT/FIPT two types of NPT. Or is NPT a different type of thread?
I think you mean MIPS and FIPS which stand for Male and Female Iron Pipe Size.
NPT stands for National Pipe Thread which is the US standard for tapered pipe threads.
Next question! Cheers, Tom