The June 2017 security patch is now available for Nexus and Pixel devices that are still being supported. This means that users should begin seeing an OTA landing on their device in the next few days. Or, users could opt to sideload the OTA and even flash the entire factory image. Obviously, flashing the factory image will take much longer, and it will also cause the device to be wiped clean, and you'll need to redownload all your apps and set everything up once again. Sideloading the OTA just replaces the files that were changed and you're good to go.
According to Google's security bulletin for this month, there are two security patches once again. There's one for June 1st and one for June 5th, which patches everything. This has been done for Google's partners to easily update their devices, since not all patches are needed for devices from LG, Samsung, Motorola and other partners. There are a few vulnerabilities in Bluetooth that were patched this month. These vulnerabilities dated back as far as Android 4.4.4 and were present in Android 7.1.2 which is currently the latest version of Android. There are quite a few vulnerabilities for Qualcomm, MediaTek and NVIDIA processors (and their components) that were also patched this month. Google has not released the exact details of these vulnerabilities - which is typical - as the company doesn't want unpatched devices to become vulnerable, and allow hackers to find a way into those devices.
Security patches don't bring anything new for users, but they are important updates to install on your device. They keep your smartphone, tablet and other devices up to date, and safe. So when the update lands on your device, be sure to install it, instead of telling it to install later on. For this update, the Pixel and Pixel XL are getting build NKG47L (there are a few different builds for the Pixel and Pixel XL, make sure you grab the one for your carrier), Nexus 6P, Pixel C, and Nexus 5X are getting build N2G47W all of which are Android 7.1.2. The Nexus 6 gets build N6F27E which is Android 7.1.1, along with the Nexus 9 getting two builds N9F27C, N4F27E both of which are also still Android 7.1.1.