Sony has started pushing out a new update to its Xperia Z5 family of devices. It's a minor, Nougat-based update that bumps the build number to 32.3.A.0.378. Aside from the Xperia Z5 range, the Xperia Z3 Plus and Xperia Z4 tablet are also getting the same update.
Sadly, it isn't yet known what exactly the update brings along. Given that the roll out has just begun, it may take some time for the update to hit your device. Meanwhile, if you feel impatient, you can manually check for it by heading to your handset's Settings menu.