The word is "symmetry", and its opposite is "asymmetry".
The second clause says that the opposite of "symmetry" is "asymmetry".
Alternatively, I could have said the following:
The word is "symmetry", and it's opposite of "asymmetry".
This would make the second clause say that "asymmetry" was the opposite of "symmetry". However, it is considerably less elegant when phrased this way.