Events are kinda “triggers” that define actions or assign values. An event is “when something happened”. There are standard events like “player pressed left mouse button” and there are custom events like “OnWaveSpawned”. Every event is unique in a means that there can only be one event for clicking the left mouse button or one event for “the wave at brewery5 has just spawned”.
Blueprints are powerful but working with them can be complicated in the first few minutes (or hours) for absolute beginners. I suggest you start with some very basic tutorials from epic - they are for sure much more boring than a strategyGame, but you will learn many valuable basics that will otherwise make you think like “huh why did this happen? What is this doing?”. Most of us started looking at some very complicated game templates, didn’t understand much and then went back to field one and started the tutorials.