This is the 15271st most frequent Polish word.
skakać
"Skakać" means "to jump."
In this sentence, 'skakać' means 'to jump', describing a person's recreational activity.
Lubię skakać na trampolinie.
I like to jump on a trampoline.
Here, 'skaczą' is a conjugation of 'skakać', used to describe the jumping behavior of kangaroos.
Kangury skaczą wysoko.
Kangaroos jump high.
The word 'skakać' is centered around the motion of jumping, in this case, while playing with a jump rope.