so how does the eviction process work then in Poland?
Badly and slowly, for example, they have to be at least four months behind with the rent.
what tenant rights do they have?
Lots, for example in some cases the right to alternative accommodation, at your expense.
Polish law is definitely weighted in favour of tenants and not landlords. I wouldn't even think about renting an apartment as a residence (rent it out as an office and stick a clause in the agreement stating that people are not allowed to live in the property, on pain of termination of agreement with 28 days' notice).