This is the 8768th most frequent Polish word.
rover
The Polish word "rover" does not exist; it might be a borrowing or misspelling. If referring to "rower," it means "bicycle" in English.
In this sentence, 'łazik' refers to a space exploration vehicle, specifically the Mars rover.
Kiedyś obserwowaliśmy, jak marsjański łazik przemieszcza się po nierównym terenie.
Once we observed how the Mars rover moved over uneven terrain.
Here, 'Rover' is a proper noun, used as the name of a dog.
Moja siostra ma psa o imieniu Rover.
My sister has a dog named Rover.
In this example, 'łazików' refers to exploration vehicles used for planetary research.