system
A chat on subreddit /r/pcmasterrace
human
You were **SO** close, it stands for Super Fucking Petite.

Jokes aside, it actually stands for Small Form-Factor Pluggable.  It's designed to let you easily convert the hand-off for your network.  

Some people prefer copper (ethernet), others prefer fiber, some need 10G whereas others require 400G.  With SFP/SFP+, you can quickly convert your port to whatever you need.  After working in enterprise networking, I really wish more consumer devices supported it.
gpt
The Asus rt-ax89x has 10gbe ethernet and 10gbe sfp+ ports