Citizens of the European Union and the European Economic Area do not need a visa to enter Poland. However they have to apply for a temporary residence permit after their arrival in Poland.
You will find more information here: https://udsc.gov.pl/en/cudzoziemcy/obywatele-ue-oraz-eogszwajcarii-i-czlonkowie-ich-rodzin/
Non-EU citizens need to apply for a visa prior to their arrival in Poland. In order to apply for a student visa, candidates need to receive an acceptance letter from the University College of Enterprise and Administration which can be issued once all the application documents are submitted. Visa policies can vary depending on the country and an acceptance letter might not be sufficient to obtain a visa in some countries.
You will find more information here: http://www.msz.gov.pl/en/travel_to_poland/visa/
Prospective students are obligated to provide the University with a copy of health insurance for the period of their studies before the academic year starts. It can be either a private insurance policy obtained in their country of origin or a voluntary health insurance in Polish National Health Fund.
You will find more information here: http://www.nfz-lublin.pl/voluntary_health_insurance.
Non EU and EEA students must apply for a residence permit after their arrival in Poland in order to legalize their stay in our country.
You will find more information here: https://udsc.gov.pl/en/cudzoziemcy/obywatele-panstw-trzecich/