This is the 16402nd most frequent Russian word.
ровной
Even, flat, level.
Here, "ровной" is an adjective in the instrumental case describing the surface state of the countertop, emphasizing smoothness or evenness.
Столешница должна быть ровной.
The countertop should be even.
In this context, "ровной" is used to describe the quality of the road as being level or without irregularities, highlighting its physical aspect.
Мы шли по ровной дороге.
We walked along a flat road.
The word "ровной" here describes the garden as being contemporaneously smooth or level, which affects the visualization of the scene depicted.