MO files: MO, or Machine Object is a binary data file that contains object data referenced by a program. It is typically used to translate program code, and may be loaded or imported into the GNU gettext program.PO files: PO files are the files which contain the actual translations. Each language will have its own PO file, for example, for French there would be a fr.po file, for german there would be a de.po, for American English there might be en-US.po.POT file: POT files are the template files for PO files. They will have all the translation strings left empty. A POT file is essentially an empty PO file without the translations, with just the original strings.
For Themes : “wp-content\themes\wplms\languages”For plugins : “wp-content\plugins\pluginname\languages”
For Themes : “wp-content\languages\themes”For plugins : “wp-content\languages\plugins”
The Global translation files are not changed when you update any plugin or theme. Only Local Translation files are changed.