The giants of Scandinavian and other Pagan people are a tribe of high spiritual beings, whose powers can rival the Gods of Asgard. They are however very different from the Gods of Asgard but respond to the same cosmological principles.
The saying "Giants" is not a right to describe those beings though. In modern-day English, the word "Giant is used to describe something very big or enormous in size. From Northern sagas, there is no indication that the jötnar ( the way Norse and Germanic tribes called them) were in did enormous.
The Typology came from ancient sources that say that the Aesir (Gods of Asgard like Odin and Thor) are the protectors and helpers of humanity, while the Giants are mostly trying to create chaos. They are considered the bringers of destruction and evil.
With that being said, they are not always playing destructive roles - meaning chaos and destruction is not the purpose of their existence, sometimes they even played constructive roles in stories.
This is plainly shown in one of the Norse sagas, where the gods create the universe out of a dead body of a killed Giant, Ymir. There, like in other Sagas, we can find an understanding of a basic ecological understanding that civilization needs balance, and its existence depends both on the constructive and destructive forces.
The gods themselves are descended from "Giants". The Gods don't look for the destruction of the "Giants", but rather keep them under control to maintain the balance of the universe.
So we see, that while the gods try to keep the "Giants" under control and away from Humanity, they also know that their existence is crucial to the balance and existence of the universe.