Wikipedia has editions for many different languages, but there is no doubt that the majority of its content is not available in all the languages it supports. The English version holds the largest volume and often an article that is available in many languages has a better English version.
You can use Google Translate to read an article if the English it's not your first language, but the translation is not always the best. If, however, you can read and understand plain English then you can try switching to the simplified English version of an article to make it easier to understand.
In Wikipedia the english version has a simplified version that you can have instantly access to it with a simple change in the URL.
If you are in English version of Wikipedia, the address in the address bar will start with "en" and it should be somewhat like this: en.wikipedia.org
If you now want to see the simplified English version then the URL should be: simple.wikipedia.org
If again, by default, the Greek language is loaded in Wikipedia, you can edit the URL address and change it to "plain". For example, if you see “el” before his name domain (which means you are in Greek Results), then replace “el” with “simple” to load the simple English page.
This trick is not always going to be useful. Wikipedia is not written using a dense and complex vocabulary and the simplified version makes things clear up to a certain extent. It requires you have an understanding of the English language to some extent. If everything had failed and you should have access to the information, try putting the simplified version into Google Translate.