Parse json into PHP variables

As stated in the comments, you need to decode the json first, using json_decode().

$data = json_decode($json);

Now, for your data. It's an array of objects, which means you'll have to loop it:

foreach($data as $obj) {
    if($obj->type == 'browsers') {
        print_r($obj);
    }
}

Example

Use json_decode() but pass in the a second parameter of true. Doing so will return an array rather than an object. You can then loop trough the array to grab each of the sets of data.

$json = '[{"type":"browsers","list":[{"key":"mobilesafari","value":3},{"key":"safari","value":1},{"key":"chrome","value":1}],"cardinality":3},{"type":"countries","list":[{"key":"US","value":3},{"key":"KR","value":1},{"key":"BR","value":1}],"cardinality":3},{"type":"languages","list":[{"key":"en-us","value":3},{"key":"pt-br","value":1},{"key":"ko-kr","value":1}],"cardinality":3},{"type":"organisations","list":[{"key":"Williams-Sonoma","value":1},{"key":"Verizon Wireless","value":1},{"key":"SK Telecom","value":1},{"key":"Oi Velox","value":1},{"key":"CenturyLink","value":1}],"cardinality":5},{"type":"platforms","list":[{"key":"iphone","value":2},{"key":"win8","value":1},{"key":"mac108","value":1},{"key":"ipad","value":1}],"cardinality":4}]';

foreach(json_decode($json,true) as $arrEachItem){
    switch($arrEachItem['type']){
        case'countries': $arrCountries = $arrEachItem['list']; break;
        case'browsers': $arrBrowsers = $arrEachItem['list']; break;
        case'languages': $arrLanguages = $arrEachItem['list']; break;
        case'organisations': $arrOrganisations = $arrEachItem['list']; break;
        case'platforms': $arrPlatforms = $arrEachItem['list']; break;
    }
}

//Output each array to the screen
echo "<pre>";
print_r($arrCountries);
print_r($arrBrowsers);
print_r($arrLanguages);
print_r($arrOrganisations);
print_r($arrPlatforms);

$data='[{"type":"browsers","list":[{"key":"mobilesafari","value":3},{"key":"safari","value":1},{"key":"chrome","value":1}],"cardinality":3},{"type":"countries","list":[{"key":"US","value":3},{"key":"KR","value":1},{"key":"BR","value":1}],"cardinality":3},{"type":"languages","list":[{"key":"en-us","value":3},{"key":"pt-br","value":1},{"key":"ko-kr","value":1}],"cardinality":3},{"type":"organisations","list":[{"key":"Williams-Sonoma","value":1},{"key":"Verizon Wireless","value":1},{"key":"SK Telecom","value":1},{"key":"Oi Velox","value":1},{"key":"CenturyLink","value":1}],"cardinality":5},{"type":"platforms","list":[{"key":"iphone","value":2},{"key":"win8","value":1},{"key":"mac108","value":1},{"key":"ipad","value":1}],"cardinality":4}]';

if( !function_exists('pre') ){/* utility function for formatted output - aids debugging */
    function pre( $data ){
        echo '<pre>',print_r( $data, 1 ),'</pre>';
    }
}

if( !function_exists('createobject') ){
    function createobject( $data=false ){
        try{
            if( !$data )throw new Exception('Bad value supplied for input data');

            /* decode the supplied data */
            $json=json_decode( $data );

            /* re-use the variable but reassign as an object */
            $data=new stdClass;

            /* Iterate through the json data and construct out output object */
            foreach( $json as $obj ){
                try{
                    /*
                        A temporary array to store each list item
                        ~ could potentially use `array_map` here
                    */
                    $tmp=new stdClass;
                    foreach( $obj->list as $i => $item ){
                        $tmp->{$item->key}=$item->value;
                    }

                    /* Assign new property to output object */
                    $data->{$obj->type}=$tmp;
                }catch( Exception $e ){
                    continue;
                }
            }
            return $data;
        }catch( Exception $e ){
            echo $e->getMessage();
        }
    }
}
/* To use new object */
$obj=createobject( $data );
pre( $obj );
pre( $obj->browsers );
pre( $obj->organisations );
echo $obj->languages->{'en-us'}; //3

This will output:

stdClass Object
(
    [browsers] => stdClass Object
        (
            [mobilesafari] => 3
            [safari] => 1
            [chrome] => 1
        )

    [countries] => stdClass Object
        (
            [US] => 3
            [KR] => 1
            [BR] => 1
        )

    [languages] => stdClass Object
        (
            [en-us] => 3
            [pt-br] => 1
            [ko-kr] => 1
        )

    [organisations] => stdClass Object
        (
            [Williams-Sonoma] => 1
            [Verizon Wireless] => 1
            [SK Telecom] => 1
            [Oi Velox] => 1
            [CenturyLink] => 1
        )

    [platforms] => stdClass Object
        (
            [iphone] => 2
            [win8] => 1
            [mac108] => 1
            [ipad] => 1
        )

)
stdClass Object
(
    [mobilesafari] => 3
    [safari] => 1
    [chrome] => 1
)
stdClass Object
(
    [Williams-Sonoma] => 1
    [Verizon Wireless] => 1
    [SK Telecom] => 1
    [Oi Velox] => 1
    [CenturyLink] => 1
)
3