This is the 17220th most frequent Russian word.
строительная
"Строительная" means "construction-related" or "building-related."
Here, 'строительная' is used as an adjective modifying 'компания' (company), indicating that the company is related to construction.
Эта строительная компания занимается возведением жилых домов.
This construction company specializes in building residential houses.
In this sentence, 'строительная' modifies 'выставка' (exhibition), indicating that the exhibition pertains to construction industry topics.
Мы посетили строительную выставку, чтобы узнать о новых технологиях.
We visited the construction exhibition to learn about new technologies.
Here, 'строительной' is in the prepositional case as part of 'на строительной площадке' (at the construction site), modifying 'площадка' (site), showing a locational aspect pertaining to construction.