As with any such question, the key to understanding the quote lies in its context. In order to understand the context, you have to look at the quote in its entirety and also consider where it is mentioned in the text. This is the full quote:
The despot is the child of violent pride,
Pride that vainly stuffs itself with food unseasonable, unfit,
climbs to the highest rim, and then plunges sheer down into defeat.
This quote is said by the Chorus as a reflection on the character of Oedipus as he continues to ignore the suggestions and advice given to him by characters such as Creon and Tiresias, the blind prophet. What this quote suggests is that Oedipus has become a "despot" because of his massive pride. The Chorus goes on to personify pride as a character who fills himself with bad food, and then rises up to a high position but only to fall down the other side into a state of "defeat." This quote therefore acts as a commentary on the failings of Oedipus as a character and in particular foreshadows his fate as a character who is defined by pride and self-importance. The way he ignores or will not listen to the words of those around him demonstrates this.