SAFT stands for a "Simple Agreement for Future Tokens".
A SAFT is the commercial instrument used to convey rights in tokens prior to the deployment of the tokens’ utility functionality.
In the U.S., the SAFT itself is a security, so it can be offered in a private placement to accredited investors in compliance with SEC rules.
Once the network functionality is deployed, the SAFT converts to TON$ which are then delivered to the SAFT investors.
As the utility value of the TON$ is now fully-functional, the TON$ are not securities under U.S. law.
A comprehensive guide to SAFTs can be found here: https://saftproject.com/