The economy of the Roman Empire was incredibly sophisticated, and had most of the trappings of the modern economic setting: currency stock and circulation (coins, bullion, trade in kind), commodities trading (mining, agricultural produce, manufacturing, raw materials, slave trade, etc), market theory (local, regional, and supra-regional interaction); banking institutions, credit, interest, investment speculation; insurance with all its trappings (risk management, adjustors, etc); real estate, rents, leans, speculation, etc; inflation and its temporary or longterm remedies; price gouging and/or price manipulation; and sophisticated contractual and legal practices underpinning it all; and on and on. It is a gigantic topic, way too big to summarize here.

The best way to get a quick understanding of various aspects of the Roman Economy is Scheidel (ed), The Cambridge Companion to the Roman Economy (Cambridge 2012), which such entries as "Roman economic thought," "Contract labor," "Raw materials and energy," and "Money and finance."

If you want to deep dive and re-read paragraphs several times before fully understanding them, then Peter Temin, The Roman Market Economy (Princeton 2013) or Duncan-Jones, Structure and Scale in the Roman Economy (Cambridge 1990). If you want to go back to Archaic and Classical Greece, then see Migeotte (ed; transl. Lloyd), The Economy of the Greek Cities: from the Archaic Period to the Early Roman Empire (Berkeley 2009).