What does the error message "Parse error: parse error, expecting `T_STRING' or `T_VARIABLE' or `T_NUM_STRING'" indicate in PHP?

The error message "Parse error: parse error, expecting `T_STRING' or `T_VARIABLE' or `T_NUM_STRING'" in PHP indicates that there is a syntax error in the code where a string, variable, or number is expected. This error often occurs when there is a missing or misplaced string, variable, or number in the code. To solve this issue, carefully review the code and ensure that all strings, variables, and numbers are correctly placed and formatted.

// Incorrect code causing the parse error
$number = 123;
echo "The number is: $number";
```

```php
// Corrected code
$number = 123;
echo "The number is: " . $number;