Mommy's tears seemed to come from somewhere else, a place inside her that she never let any of us children visit, and even as a boy I felt there was pain behind them.Explain this quotation ?

The boy obviously realizes that there are things about his mother and her past that he is unaware of. Mommy cries for a reason he cannot fathom; this is typical of what mothers everywhere do when they want to protect their children. What he knows for sure is that she cries and crying often means pain.

James, as a child, never knew his mother's past. He never knew her pain about her harsh childhood and her family disowning her. He never knew the conflicting emotions around ethnicity and the tough relationships that made her who she was. All James knew is that there was pain behind her.