Final answer:
The speaker first experienced the impact of racism at the age of five, as they refer to needing to explain societal issues to their own five-year-old son.
Step-by-step explanation:
The question appears to be referencing a historical speech or document that discusses personal experiences with racism. Assuming the excerpt is from an account of a person's childhood experience, the age mentioned within the context of the question is five years old. The speaker refers to having to explain a complex and painful societal issue to their young child, who is at the inquisitive age of five, likely indicating that this was the speaker's first significant encounter with the impacts of racism on a personal level.