I’m not quite sure how to articulate this, but I’ll try,
Variables have many many uses. Some basics points are that variables are called variables because they can change. Lets say you have a calculator app with a variable called runningTotal. every time something is added or subtracted etc. runningTotal changes. This is one reason why you cant just manually type things in every time, in programming there’s automation changing your variables.
variables are also used when you dont know what the value will be at all, like for user input. in your example you yourself could usually type “LONDON” but if its user input that sets the variable, the user could type “LonDon” or any other variation, and if you need that to be all capital no matter what at the end, you have a function that can make sure of that.
‘+’ isn’t to separate words. When you use + between 2 strings (or 2 variables representing strings) you get the 2 strings combined into 1 string. If you use it between 2 numbers you get the two numbers added together.
hope that helps,
theres already been a couple decent responses it seems, by the time I finished typing.