Woo-commerce multilingual feature

I have a question about multilingual plugin. WooCommerce and many other WP plugins have ONLY POT file in language folder but not all language files. But it have multilingual feature….

My question is that how WordPress is converting it into other languages because it does not have language files in language folder?

Second question is my custom plugin also have POT file in language folder but not getting translate into other languages by WordPress.

Please guide me. Any help will be appreciated.

Thanks