$post_author: WP_User Object
(
    [data] => stdClass Object
        (
            [ID] => 122
            [user_login] => mac-slavo
            [user_pass] => 1efe1b3388cc0ba724a63650ea8cec7e
            [user_nicename] => mac-slavo
            [user_email] => [email protected]
            [user_url] => 
            [user_registered] => 2011-12-07 15:12:04
            [user_activation_key] => 
            [user_status] => 0
            [display_name] => Mac Slavo
            [type] => wpuser
        )

    [ID] => 122
    [caps] => Array
        (
            [contributor] => 1
        )

    [cap_key] => wp_capabilities
    [roles] => Array
        (
            [0] => contributor
        )

    [allcaps] => Array
        (
            [edit_posts] => 1
            [read] => 1
            [level_1] => 1
            [level_0] => 1
            [delete_posts] => 1
            [email_single_user] => 1
            [contributor] => 1
        )

    [filter] => 
    [site_id:WP_User:private] => 1
)

get_the_author_meta: 

$bio: Mac Slavo [send him mail] is a small business owner and independent investor.

$bios: Array
(
    [0] => Mac Slavo [send him mail] is a small business owner and independent investor.
)

Mac Slavo [send him mail] is a small business owner and independent investor.