First of all, let's look at the difference between indirect and direct characterization. Direct characterization is when an author or, in the case of Kaffir Boy, narrator directly reveals something about the character. For example, if the author or narrator tells the reader that the character is a kind and sympathetic person, that is direct characterization. Indirect characterization is when an author shows the character's personality through what he does, says, and even through how he dresses. For example a reader would presume that a young girl dressed in boys's clothes is a tomboy.
Examples of direct characterization include page 33, when the character shows hatred for his father for beating him --
The next day, as I nursed my wounds, I told my mother that I hated him and promised her I would kill him when I grew up.
-- and page 23, when he follows the police because, as he states, he was "curious" about where the police were taking his father. He states his curiosity was greater than his fear because "I hated them more than I feared them."
Example of indirect characterization are in everything the character says, thinks, and does. Two examples include page 5 when the character has a "nightmare in which throngs of black people sprawled dead in pools of red blood." This highlights his fear for the racism occurring around him on a daily basis and on page 11 when, finding himself alone in a dangerous situation with his younger brother and sister, he yells at his brother,
"Shut you, you fool!" I yelled at my brother, but he did not quiet. I then uttered the phrase, "There's a white man outside," which to small black children had the same effect as "There's a bogeyman outside."
This highlights his extreme vulnerability.