A Data Table in Unreal Engine is a spreadsheet with a type. You define a row struct, the table holds rows of that struct, and gameplay code looks a row up by name at runtime.
It is the right place for static data that designers should own without asking a programmer: weapon stats, enemy tuning, loot tables, dialogue keys. It is the wrong place for anything that changes while the game is running, because a table is an asset and assets are read only at runtime.
The walkthrough is in How to Use Data Tables in Unreal Engine 5, and Epic's reference is Data Driven Gameplay Elements.
