With maCOS 10.14.5, you’l find mainly bug fixes, security improvements, and other under-the-hood enhancements. In other words, don’t expect any user-facing changes or features. It’s really a marginal update that’s meant to improve how your system works.
The new software can be installed by heading over to the System Preferences section of the Settings app. From there, hit “Software Update” and you should spot the upgrade ready to be download. Hit download and wait for it to finish installing. You’ll want to plug in your MacBook before installing the update to ensure you don’t run out of juice. Otherwise, sit back and be patient.