The Polish Government decided that from 13.06 the Polish borders will be opened. However, that does not apply to all countries! Before coming to Poland it is your responsibility to contact the Border Guards and ask whether it is possible for you to come back and whether you will be quarantined, or not. The situation is changing all the time, so keep yourself up-to-date.
Additionally, there might be restrictions in your own countries, or the countries whose borders you are going to cross on your way to Poland, so make sure that you research everything thoroughly before planning your trip back.