Data is not only vulnerable to outside threats, but also to malicious intentions and the negligence of insiders. While there are several features inside Macs themselves that protect against certain types of data breaches such as FileVault and Open Firmware passwords, these offer no protection when the users themselves are the perpetrators.
This is where DLP solutions for Macs come into play. Through predefined policies, they can keep track of sensitive data, block or log its transfer or delete or encrypt it when found on the Macs of unauthorized users. It can also help you monitor all ports and devices on Macs, flagging any suspicious activity.
You can read more about how to choose the best DLP solution for Macs here.