The security features of using Git might not be straightforward as they depend on what you're using it for, but here are some ideas.
Version Control - duh. But if you're using Git to track configuration files, Software Defined Networking, infrastructure provisioning code, or a deployed application, and suddenly things don't work. You can (theoretically) revert to a known good configuration, see what changes were made, and see who made the changes. This provides auditing and (a form of) disaster recovery. Furthermore, if it's used to manage puppet configs or Infrastructure as Code, it can serve as self-documentation. All of these can protect against downtime.
Hashing - Though SHA1 is considered much less secure now that an intentional collision has been demonstrated, it's still unreasonable to expect almost any malicious actors in a reasonable amount of time to be able to modify anything in your git repository that would stand against scrutiny.
Those are really the only benefits that come to mind, but using something for a version control of configuration files is a huge deal for enterprises. When you have many people capable of "fixing" configurations on your networks and servers, version control provides a very strong mitigation. Generally it would need to be paired with configuration management like Puppet or Salt.