This is the 17716th most frequent Russian word.
удобная
"Convenient" or "comfortable."
The word 'удобная' is used here to describe the comfort quality of the sofa. It modifies the noun with an adjective describing physical comfort.
Этот диван очень удобный.
This sofa is very comfortable.
Here, 'удобная' is used to describe the staircase as being easy to use or practical, showcasing usability or convenience.
Мне нравится эта удобная лестница.
I like this convenient staircase.
In this sentence, 'удобное' (masculine form of 'удобная') describes the solution as being suitable or fitting for the task, demonstrating suitability or appropriateness.