Remove Query Strings from Static Resources

Hi!

When I test my site on Pingdom I get this message: Remove Query Strings from Static Resources.I wonder if it's safe to paste following code into the code snippet plugin?

function _remove_script_version( $src ){
$parts = explode( '?', $src );
return $parts[0];
}
add_filter( 'script_loader_src', '_remove_script_version', 15, 1 );
add_filter( 'style_loader_src', '_remove_script_version', 15, 1 );

I don't know if it's important to fix this, as my site get about full score in every other aspect, loading in 300 ms. I don't even know what it means to remove query strings?

There was a warning about pasting this code into the function.php as it could mess up the theme, that's why I'm asking you first.

Thank you!