If memery serves me right:
train rate: Unit production
world train rate: Specialist/Generals discount for next
Construction rate: Building production
world construction rate: National wonders production
Create: Faith and gold purchases
world create: Global projects (Apollo, Manhattan)
Per era modifier: Affect all other bonuses, reducing costs of maintenance, units, purchases, etc. It's multiplicative not aditive, so when AI enters classic with 50% unit prod and 5 per era, will have 52,5% discount, not 55% discount.