A bunch of farmland?
Yes. Along with some small cities, and most importantly the only rail lines and major roads that allow supplies from Russia to reach front line troops further south.
That cut off tens of thousands of Russian soldiers from food, ammunition, fuel and most importantly artillery shells. Which is why there are miles long convoys of Russians trying to escape to the east.
Some of the recaptured territory also allows Ukrainian artillery to reach what were previously safe Russian rear bases and shipping areas.