What does Genesis 42:23 mean?

In the prior verses, Joseph's ten older brothers are confessing their guilt for selling him into slavery twenty years earlier (Genesis 42:21–22). They speak so openly because they assume he couldn't understand a word they were saying. They have no idea the Egyptian governor who commands them is their enslaved brother, raised to a position of incredible power (Genesis 41:42–45; 42:8).

To this point, Joseph had used an interpreter to communicate with them, translating between his Egyptian language and their Canaanite or Hebrew tongue. Official business was likely conducted only in Egyptian, but even then, the interpreter was a useful part of Joseph's deception. His secret is strained, however, as he emotionally reacts to what his brothers are saying (Genesis 42:24). That reaction will happen more than once (Genesis 43:30), proving that Joseph's reasonable anger (Genesis 42:7) is tempered by a merciful sense of love.