The value of x will be 6. The unary plus operator (+) before a variable converts it to a number if it's not already one. So +x converts the string '5' to the number 5. Then, 5 + 1 evaluates to 6, which is assigned back to x. This is different from let x = '5'; x = x + 1;, which would result in the string '51' due to string concatenation when the + operator is used with a string and a number.