Displays the total of all elements for the current entry. Element types can be specified with “element_type” parameter.

Simplified case example:

{exp:channel:entries channel="your_channel" limit="10"}
    Total elements: {custom_field:total_elements}
    Total tables: {custom_field:total_elements element_type="table"}
    Total plain text elements: {custom_field:total_elements element_type="text_field|textarea"}

    {!-- Alternative in the content element tag pair --} 
    {custom_field}
        {total_elements}
    {custom_field}
{/exp:channel:entries}

Note: Available from Content Elements version 1.7.0