Contacted a few brokers and had a 6 month assignment within a week. They took 10% of all my invoicing
He's referring to contracting, where you work for one client at a time, almost identical to like an employee would but for the duration limit (and likely a company in between you and them to solidly the facade).
In contrast to what most people would call freelance, where you work for multiple clients at the same time, i.e. a dev agency of one.
The contracting agencies don't do any permanent position, they only do medium-to-long term contracts (3-24 months). The biggest is Northern Europe is probably https://www.verama.com/ (ex E-Work)
Even gets used for fixed term employees.
computer futures in europe years ago wanted to double my rate
Worked until I found something better.