how to get image url from meta value?

This is a serialized array value in the database. WordPress serializes arrays as a way of storing structured data in the database.

You need to use get_post_meta() to get the post meta data value, something like this:

$array = get_post_meta($post_id, 'meta_data_key_name', TRUE); // add the meta data key name

Then, you can print the content of the $array:

print_r($array);

Or echo it like:

echo $array[0];
echo $array[1];

That’s of course if it is an indexed array (which you will find out when you print_r() it).