What is the error message "Fatal error: Unsupported operand types" indicating in the PHP code provided?

The error message "Fatal error: Unsupported operand types" indicates that the code is trying to perform an operation (like addition or subtraction) on incompatible data types. To solve this issue, you need to ensure that the operands being used in the operation are of compatible types. This can be done by explicitly converting the operands to the correct data type before performing the operation.

// Example code snippet to fix the "Fatal error: Unsupported operand types" issue
$num1 = 10;
$num2 = "5";

// Convert $num2 to an integer before performing the addition operation
$result = $num1 + (int)$num2;

echo $result;