I believe the query statement is incorrect.
It is better that you check first for the variable $_POST['searching'], whether that is it empty.
You can use this
echo $_POST['searching']; to see whether that it is empty
then the query should format in this way
$search_result = @("SELECT * FROM jokes WHERE title LIKE '%".$searching."%' OR language LIKE '%".$searching."%' OR author LIKE '%".$searching."%' ORDER BY id DESC");
then make another echo to check whether that the query is correct.
just remember that " is use to open and close a string in php, and you use . to combine two string. then I believe that you need a ' to enclose a string for the database to search base on a string.
or you also can do in this way
$query = "SELECT * FROM jokes WHERE title LIKE '%".$searching."%' OR language LIKE '%".$searching."%' OR author LIKE '%".$searching."%' ORDER BY id DESC";
//if your $query got a syntax error, the page will load error.
echo $query;
$search_result = @($query);