The expression 5 + true evaluates to 6. When using arithmetic operators other than + with a boolean value, JavaScript converts true to 1 and false to 0. So, 5 + true becomes 5 + 1, which equals 6. This is another example of type coercion in JavaScript, where non-numeric values are automatically converted to numbers in numeric contexts. In this case, the boolean true is coerced to the number 1 for the addition operation.