You have a string consisting of some comma separated sub-strings (see the following). With those sub-strings, you want to form an array.
$languages = “Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday”;
You can use explode() function to split the above string separating by comma and create an array. See the following example-
<pre> <?php $languages = “Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday”; $lan_arr = explode(‘, ’, $languages); print_r($lan_arr); ?> </pre>
Array (  => Sunday  => Monday  => Tuesday  => Wednesday  => Thursday  => Friday  => Saturday ) [wpdm_file id=68]
How it works:
The explode() function split the string(second parameter – $language) into smaller pieces separated by the separator defined as the first parameter(, ).