Give a values for array keys PHP

$columns = array( 'title', 'client', 'date', 'product', 'status' );

This is print:

Array
(
    [0] => title
    [1] => client
    [2] => date
    [3] => product
    [4] => status
)

I want to give values for the $columns array to be like this:

Array
(
    [title] => Subject
    [client] => Requester
    [date] => Requested
    [product] => Product
    [status] => Status
)

I have try to make something like this:

$columns['title']       = 'Subject';
$columns['client']      = 'Requester';
$columns['date']        = 'Requested';
$columns['roduct']      = 'Product';
$columns['status']      = 'Status';

But it's not working it merges the two arrays and print this:

    Array
(
    [0] => title
    [1] => client
    [2] => date
    [3] => product
    [4] => status
    [title] => Subject
    [client] => Requester
    [date] => Requested
    [product] => Product
    [status] => Status
)

The code that prints the final result is this:

$columns = array( 'title', 'client', 'date', 'product', 'status' );

$columns['title']       = 'Subject';
$columns['client']      = 'Requester';
$columns['date']        = 'Requested';
$columns['roduct']      = 'Product';
$columns['status']      = 'Status';

If i understood you correctly you want to add these data

$data = ['Subject', 'Requester', 'Requested', 'Product', 'Status'];

to the columns name that you mention

$columns = array( 'title', 'client', 'date', 'product', 'status' );

so it would be something like this one

$columns = array( 'title', 'client', 'date', 'product', 'status' );


function prepareArray($columns){

    $humansTitles = [
        'title' => 'Subject',
        'client' => 'Requester',
        'date' => 'Requested',
        'product' => 'Product',
        'status' => 'Status'
    ];

    $res = [];

    foreach($columns as $col){
        $res[$col] = $humansTitles[$col];
    }

    return $res;
}

print_r(prepareArray($columns));