A recession is a period when economic activity declines, unemployment spreads, and drops in prices and wages become conspicuous.
Literal
Recession [quotative-とは] economic-activity's decline, unemployment's spread, prices [and-や] wages [etc-など] fall [subject-が] conspicuous period thing [formal copula-である].
~とは~のことである is a definitional pattern: 'X is (defined as) Y.' 目立つ = 'to be conspicuous.' Dense economic vocabulary with など marking a non-exhaustive list.