This is the 797th most frequent Swedish word.
förändras
To change; to undergo change.
Here, 'förändras' is used reflexively to indicate that the subjects (people) undergo change themselves.
Människor förändras ofta med tiden.
People often change over time.
In this sentence, 'förändras' describes a necessary transformation of the subject (society).
Samhället måste förändras för att möta framtidens krav.
Society must change to meet the demands of the future.
Here, 'förändras' emphasizes a natural and gradual process of change involving the subject (leaves).