What is general fluid intelligence?
Just did some more reading, going to answer my own question:


  Fluid intelligence (Gf) refers to mental operations that an individual uses when faced with a relatively novel task that cannot be performed automatically. Inductive and deductive reasoning are generally thought to be the hallmark narrow-ability indicators of Gf. Examples of Gf abilities are: Induction, Pigatian Reasoning, Quantitative Reasoning and Speed of Reasoning.


By comparison Crystallized Intelligence (Gc):


  Gc refers to the breadth and depth of a persons acquired knowledge, and the application of this knowledge. Examples of Gc abilities are: Language Development, Lexical Knowledge, General Information, Information about Culture, General Science Information, Communication Abilities etc..


Reference:
Reynolds, C. R., &amp; Fletcher-Janzen, E. (2007). Encyclopedia of Special Education (Vol. 1). Wiley.

If anyone has anything better or more to add, please do.