Unfortunately, it's hard for me to understand
adds a message in the form '{-Variable.Variable1 -}'! = ''
and further commands are incomprehensible to me
I tried every combination but I don't know the programming language so nothing will happen
It is very basic logical action, You have to get around it, otherwise, you will be stuck.
Make tests and read articles about if logic to understand.
I totally agree it is confusing at first, but once you will start to understand it will get easier with time.
To explain what is in your picture:
Blue action takes text for page and saves it into Variable8.
Then the next action is logical IF action checks this Variable8 and in this case, it checks if it is empty or not.
'{-Variable.Variable8-}'! = '' - Means Variable8 IS NOT Empty
Logical operator != from wiki you see means IS NOT
So if Variable8 IS not Empty then IF action returns TRUE value what means it will continue to work by Green exit.
If it will be empty it will return False what means it will continue to work by the red exit.