literal: I know fire
Deeper meaning: this person knows what it's like to be filled with hate and anger, this represents the fire he feels.
Black men are being victimized because of the accusation that they raped white women, but of this there is no history, it was a motive that was used to justify the lynching. That blacks were inferior to whites and therefore there was justification for this society as a whole to be overthrown. Also because they were becoming a primitive race.
Pa is ashamed of himself because he’s irritated by the fact that Noah is quiet and slow, in contrast to Ma, who has unconditional love for al members of her family.
