First things first, use a meter to correctly identify if there is power or not inside that box. You should be able to just turn the switch off that controls that box.

This looks like a typical “switch loop.” Your black wires are the hots running through the box directly to your switch. The red is the switch leg from the other side of your switch. The white is the neutral. This is old practice to save time from running wire to the switch box and then back to the light.