Go to Languages > Settings
Click on the settings link of the Custom post types and Taxonomies module. Below is an example displaying a custom post type ‘Book’ and its custom taxonomy ‘Genre’. The checkboxes allow you to choose whether to enable the languages and translation management for these post types an taxonomies.
Note: To correctly display the languages columns and metabox for custom post types and taxonomies, plugins or theme authors must use the same actions and filters as WordPress. Otherwise there is now way for Polylang to add its own interface.
Note for developpers: By default, Polylang displays the post types and taxonomies in the settings for which the parameter ‘public’ is set to true. Other won’t appear. You can use the wpml-config.xml file or the filters ‘pll_get_post_types’ and ‘pll_get_taxonomies’ to change that.