www.websitename.com has three languages
by going to each of those links you will get all the remaining pages in the selected language.
You can also visit a page by manually typing the sub-folder at the front and automatically change the language :
However by default apart from the main page e.g
www.websitename.com/en the rest of the pages won't have the sub-folder appended to the URL so the links will be
www.websitename/test1.php, www.websitename/test2.php etc.
Will Google or other search engine index the different of those or it will be only one version indexed because they are missing the language in the path?