Right after arrival
In Poland, there are some very popular among foreigners airports. These include, among others, Warsaw Chopin Airport, the port Reymont in Lodz. These ports handle most of directions and probably if you are going to visit Poland you'll land at one of them.
After arrival you should take a taxi to get to place where you want to stay during your stay in Poland. Of course, nothing stands in the way to start your tour from the first day, so you might want to ask the taxi driver about the nearest monument or a place worth visiting.
What is taxicab? Wikipedia explains
A taxicab, also known as a taxi or a cab, is a type of vehicle for hire with a driver, used by a single passenger or small group of passengers, often for a non-shared ride. A taxicab conveys passengers between locations of their choice. This differs from other modes of public transport where the pick-up and drop-off locations are determined by the service provider, not by the passenger, although demand responsive transport and share taxis provide a hybrid bus/taxi mode.
Taxi - are they better than trains or buses
In every major city we have a choice about the means of transport. You may for example use the public transport, train, or at least your own car. You may even order a taxi, but some people say they are too expensive, so do not even take them into consideration.
However, the taxi is a convenient way carrier to long journeys. Most of them are equipped with air conditioning and other amenities, so the ride even in the sweltering heat is not exhausting. As for the cost of a taxi ride you can argue whether it is expensive or not. It must be remembered that the cab driver still has to get back to their city after completing the course.