The element variable {ce_last} is parsed inside every element to indicate if it is the last element for this entry_id (across all element types). It has a boolean value of true (1) or false (empty) used for conditionals.
Simplified case example:
{exp:channel:entries channel="your_channel" limit="10"}
{custom_field}
{heading}
{value}
{/heading}
{wysiwyg}
{value}
{!-- This text will be printed only after wysiwyg which is also the last element in entry --}
{if ce_last}<p>This wysiwyg is printed as the last element.</p>{/if}
{/wysiwyg}
{text_field}
{value}
{/text_field}
{/custom_field}
{/exp:channel:entries}