This is the 1347th most frequent Russian word.
экономической
Relating to economic.
Here, 'экономической' is an adjective modifying 'теории', indicating that the theory is related to economics, showcasing its descriptive property.
Она занимается изучением экономической теории.
She is engaged in studying economic theory.
In this sentence, 'экономической' modifies 'ситуацию', providing context about the situation's nature, indicating it pertains to economics.
Мы обсуждали текущую экономическую ситуацию в стране.
We were discussing the current economic situation in the country.
'Экономической' is modifying 'системы', describing the system as pertaining to or belonging to the domain of economics.