It would be challenging to define the Belgian Saison to any one set of attributes- from the range of colours to the various characterful yeasts that ferment them.
That said, there are a few factors we can look at. Firstly, Saisons are ales, meaning they are fermented at high temperatures in which the yeast creates a lot of fruity and spicy notes- esters, and phenols respectively. They also have fairly high carbonation, as a result of being bottled conditioned much like Champagne. They are also usually very dry and have firm bitterness.
Secondly, we can look at the particular strain of yeast and hop selection that can also start to differentiate Saisons. Saison Dupont for instance, has one of the most interesting and expressive yeast cultures in the world. In the book on Farmhouse Ales, there is a whole chapter just on this specific yeast!
When it comes to hop selection you can look at Boulevard from Kansas, a very traditional Saison in a lot of ways, but employing American style hops to give punchy citrus notes and a little more bitterness.
But let’s take New World hops in Saisons to the extreme, like in the beer we just made with North Brewing! It’s called Bloom, and it’s got all the hallmarks of Saison with it’s firm bitterness, high carbonation, and yeast character; only we’ve added a liberal dosing of Saaz, Hallertau Blanc, and Galaxy hops to give a tropical boost along with some spicy backbone.