You can create a maximum of 300 New Orders per account per 3 hours. A new order is created each time you request a certificate from the Boulder CA, meaning that one new order is produced in each certificate request. Exceeding the New Orders limit is reported with the error message
too many new orders recently.
Subject to other rate limits, (50 certificates/registered domain/week, 5 duplicates/week). It means you can issue for 30000 domains (300 orders, assuming none fail, with 100 domains per certificate) every three hours.
It's "orders," so yes.