Gabums on "custom fields and strings"

Good afternoon,

I'm trying to get the value of one of my custom fields but it keeps returning "array array array". I figured it was because there were nested custom fields. When I broke it down, I got this:

s:17:"content_main_area";
		a:4: {
			i:0;
			a:6:{
				s:20:"dynamic_element_type";
				s:9:"_text_box";
				s:7:"pb_area";
				s:17:"content_main_area";
				s:6:"_sizer";
				s:10:"two-thirds";
				s:9:"stb_title";
				s:15:"Paying for Care";
				s:11:"stb_content";
				s:1875:" $mydata = '

So it appears to me that my custom field contains a string within a string. I'm trying to get make something like this:

$custom_field = get_post_meta($post->ID, $zn_meta_elements['content_main_area']['stb_content'], true);

With $zn_meta_elements as my custom field and "content_main_area" and "stb_content" are the strings. The goal is to get the value of "stb_content" (which might be $mydata????). It seems my syntax is off and all my google searches are now showing purple links.

Can anyone point me in the right direction? Thanks so much!

Cheers!