This is the 5629th most frequent Polish word.
widoczne
Visible.
Here 'widoczne' functions as an adjective describing 'zmiany', indicating that the changes are clearly seen or noticeable.
Widoczne zmiany są efektem ciężkiej pracy.
Visible changes are the result of hard work.
In this sentence, 'widoczne' acts as an impersonal adjective used to describe a state ('było widoczne'), emphasizing that the visibility of the satisfaction is evident.
Było widoczne, że wszyscy byli zadowoleni.
It was visible that everyone was satisfied.
Here 'widoczne' serves as an adjective modifying 'światła', specifying those lights that can be seen on the horizon.