“Political Economy” refers to the pre-war term for the discipline of Economics. However, because the discipline of 20th century economics evolved to emphasize Macro-Economics and Econometrics, we use Political Economy today to refer to the study of institutions that assist in the voluntary organization of production (which is what capitalism means), by allowing individuals to cooperate in production, and providing them the incentive to cooperate in production.
These institutions include numbers, counting, accounting, money, banking, and interest, private property, shareholder property, common property, promise, contract, and common law. Legislative and Regulatory law, fiat money, fiat credit, Redistribution, Fiscal, Trade and Monetary policy.
In practical terms we tend to separate academic economics: macro economics and econometrics into short term spending and policy tactics, from political economy: the long term effects of formal institutions (governmental institutions etc) and informal institutions (manners, ethics, morals, norms, traditions, myths, eduction and religion).
(I work in Political Economy not Macro Economics.)
https://www.quora.com/Is-political-economy-a-discipline-How