Hi @jpcastro4
It means that you don’t need to use wp_insert_post() in that filter anymore. ACF 5 will create it for you automatically based on the new_post argument. This page should give you more idea about it: http://www.advancedcustomfields.com/resources/using-acf_form-to-create-a-new-post/.
You still can use it or use acf/save_post instead.
I hope this helps.