A PO file consists of multiple entries, each of which contains a link between a source untranslated string and its its corresponding translation. All entries in a given PO file usually refer to the same project, and all translations are expressed in the same target language.

important

Localizify supports po, pot, and mo file types. If you export translations in .pot format, only the terms are exported.

Documentation

GNU Web site
Read more About the PO format