The plus sign (+) is a binary operator indicating addition, such as 2 + 3 = 5. It can also be used as a unary operator whose operands remain the same (+ X means the same as x). When you need to emphasize positive numbers, especially negative numbers (+ 5? 5) This representation can be used for comparison.
Depending on the mathematical system under consideration, the plus sign can also indicate many other operations. Many algebraic structures have operations called addition operations or equivalent. The plus sign is usually used to indicate only the swap operation.