wordpress custom post type

the current cpt ui menue for adding new post is different and updated from the video. it now says post type slug and has a description under saying "The post type name/slug. Used for various queries for post type content. Slugs should only contain alphanumeric, latin characters. Underscores should be used in place of spaces. Set "Custom Rewrite Slug" field to make slug use dashes for URLs." Then under is the Plural Label box to fill that says " Used for the post type admin menu item." Then under is the singular label area box that says" Used when a singular label is needed." Then under is the add post type button. i fill them out like in the video and it gives an error star by each box and at the top the box that appears to describe the error says"Please choose a different post type name. portfolio matches an existing page slug, which can cause conflicts. " can anyone help with the new way that this is supposed to be filled out?