latter half of a Diet session; post-budget Diet period
Refers specifically to the part of a Diet session after the budget has been passed, often used in political news.
In the latter half of the Diet session, deliberation on important bills gets into full swing.
Refers to the ordinary Diet session as a whole, while 後半国会 specifically denotes the period after the budget is passed.
Compound of 後半 (latter half) and 国会 (Diet, parliament). The term is used in Japanese political contexts to describe the latter part of a Diet session.