A white savior is a type of character in a narrative (like a movie or book) who is a white person who rescues and helps people who are not white. They often come in and make big changes to the lives of the people they're helping, while they almost never experience any sort of bad consequences or changes to their own lives. The issue with this type of character is that it often paints a problematic picture of the relationship between white people and people of color in the world. It implies that only white people can help people of color, or that white people are better than people of color in some way, and this can be seen as offensive and disrespectful.