For example: a new trait, new console cheats, objects with new functionally, new UI functionality, etc. These Mods may include script code, but not always.
For example: new hair, new clothing, new furniture, etc. Sometimes just referred to in The Sims community as “CC”. Let's start by defining some terminology: On first launch after the Update is applied you will be shown a dialog at the main menu indicating that Mods have been disabled. The SimsTM 4 version 1.13 (released December 2015) adds a new feature that will disable all Mods when the game is updated via Origin. Learn about the new disable Mods feature, the Maxis policy towards Mods and how to safely re-enable Mods. Source: The Sims 4 - Mods and game updates Included below is the whole text, but basically it says that Mods will be disabled during the latest updates.
The first of which concerns if you have mods installed in game. EA made one of two announcements that will be coming with the big patch in December.