This is quite amazing question.
To explain an automation to manual testing guy bit tricky & easy both at the same time.
Tricky means what all the areas are you going to cover.
Easy means the automation tester when start with Selnium IDE (Drop Down concept) it will ease to understand first but when it comes to coding it will be not.
Automation will make our work ease. Instead of testing same set of repeated data it will be frustration for tester to do same work again & again if we code it it will make our work easier.
There are many automation tools in market which is Codeless (need not to write code for it ex RPA). If any one learns it will be easy to automate the set of repetative tests.