The at sign (@) is used as error control operator in PHP. When an expression is prepended with the @ sign, error messages that might be generated by that expression will be ignored. If the track_errors feature is enabled, an error message generated by the expression and it will be saved in the variable $php_errormsg. This variable will be overwritten on each error.
PHP Notice: Undefined variable: errormsg in /home/fe74424b34d1adf15aa38a0746a79bed.php on line 5
Failed in opening the file: error: ''
It will execute only statement 1 and display the notice message
PHP Notice: Undefined variable: hello.
Note: The use of @ is very bad programming practice as it does not make error disappear, it just hides them, and it makes debugging a lot worse since we can’t see what’s actually wrong with our code.
References: Error Control Operators