5-302. ASSIGNMENT OF THING IN ACTION. In the case of an assignment of a thing in action, the action by the assignee is without prejudice to any set-off, or other defense existing at the time of, or before, notice of the assignment; but this section does not apply to a negotiable instrument transferred, in good faith and upon good consideration, before maturity.

Does anyone know what this paragraph means?

A rational approach to an answer:

Maybe a simpler question:

Who does this apply to?

Maybe a contextual question:

In what real life situation does this become applicable?

Maybe formulate a plan to figure it out:

Should I make a list of vocabulary and define then review again?

Where should I look for the definitions of these words, some of them have multiple meanings?

A poetic answer: 

Nothing may be what it is not, except our symbols they excise us.  Nothing may be what it is not accept our symbols, except us.

Social critique: The individual is harmed when drown in a sea of abstractions which bind him.