The expression "-1" OR 3+667-667-1=0+0+0+1 can be described as a mathematical equation that demonstrates the equality between two sides. On the left side, we have the negative number -1, and on the right side, we have a series of additions and subtractions that ultimately result in the sum of 1. The equation shows that by carefully arranging the numbers and operations, it is possible to balance both sides to achieve an overall total of 1.