これだと？
$a=["a","b","c"];
print_r($a);
Array ( [0] => a [1] => b [2] => c )
これは？
$a["hoge"]=["a","b","c"];
print_r($a);
Array ( [hoge] => Array ( [0] => a [1] => b [2] => c ) )
これは
$a["hoge"]["foo"]=["a","b","c"];
print_r($a);
Array ( [hoge] => Array ( [foo] => Array ( [0] => a [1] => b [2] => c ) ) )
