This notice means that a variable that is in place for output or manipulation in your script has not been initialized or defined prior to using it.

How can i fix it

At the top of your PHP script you can simply initialize the variable names with an empty value, or wherever it makes sense to define them. Most times on top is best. After it is initialized the notice will go away and you can use those variables for output or anything else.

$var1 = ""; // initialize blank or place any default value upon creation
$var2 = ""; // initialize blank or place any default value upon creation