This is the 16667th most frequent Russian word.
сидячего
"Сидячего" means "sitting" or "sedentary" (genitive or accusative case).
Here, "сидячего" modifies "места" to describe a seating position.
Я приобрел билет сидячего места.
I purchased a ticket for a seated place.
"Сидячего" describes "образа жизни" to indicate a lifestyle characterized by a lot of sitting.
Эта работа подходит для людей сидячего образа жизни.
This job suits people with a sedentary lifestyle.
"Сидячего" relates to "положения" to define the seated state.