Install for Better Battery Management
The main feature of this update is the Battery Health Management feature that should help keep your MacBook, MacBook Pro, and MacBook Air battery healthier longer. This can translate into longer battery life over the time you own your Apple notebook. This feature is coming to Mac notebooks with the Thunderbolt 3 ports.
This new feature changes up the charging pattern for your MacBook Pro battery, which will preserve the battery health over time. In some cases, this means that your MacBook Pro will not charge to full every time you plug it in. Charging to full every time can reduce the overall battery capacity and in turn reduce battery life.
Apple uses a similar feature on the iPhone and has for several years. If you decide that you don't want to use the Battery Health Management feature on your Mac it is something that you can turn off.