1. Open en.po file in POEDIT (https://poedit.net/)

2. Translate all strings into your language

3. Save it. Name the .mo file according to this format

videopro-{language_code}.mo

For example, language_code for German is de_DE, so the file name will be

videopro-de_DE.mo

4. Put the .mo file in /languages/ folder of plugin