To phrase it in more statistical terms it would be something like "take into account how selection bias has changed your impressions of things."

E.g. as a white male in a liberal western nation I intuitively think buying food or finding a place to live is easy, so might not credit reports of someone else finding it difficult. But if prejudice against a group I am not part of was endemic I wouldn't be aware of it. So checking your privilege is a reminder that your experience may differ from others and to be aware of that.