The national language for Poland is Polish. You will sometimes be able to find English versions of websites or documents. The best thing to look for is a tiny Union Jack in the corner of a website.
If you use the Chrome browser, Google Translate will translate a website from Polish to English. The thing to note is that it only translates the HTML. If there are images with words in them, the words will not translate.
PDF's present another challenge. Chrome will not translate a PDF. But you can upload a PDF to Google Translate to create a translation.