There are a number of possible scenarios. If they hold it against the possibility of a Trump win in November, it becomes territory to swap in an enforced peace deal. In the more immediate term it will force Russia to redeploy forces from territory it holds in Ukraine - if nothing else, it is going to bring Russia’s glacial advances in the southeast of the country to a final halt. With Russia on the back foot (there are no significant fortifications, so Ukraine is not attacking entrenched positions) there are opportunities for Ukraine to destroy significant amounts of Russian military potential, both men and equipment. After reading military historians and strategists for more than 2 years now the one thing I know they all agree on is that war is about destroying your enemy’s ability to attack you much more than it is about taking territory.
However, don’t underestimate the significance of the fact that they have gone so far into Russia, and so quickly. There are strategic assets they can reach from where they now are, including railways hubs and possibly even a nuclear power station.
The Ukrainian leadership has been so tight-lipped about this, in truth nobody really knows what the plan is. However, you’ll find some informed speculation if you read Mick Ryan, a retired Australian army general, who has written about it here:
https://open.substack.com/pub/mickry...rational-phase