What it looks like is that you are calling the State() function inside its own monobehavior as if you were referencing it from another script. Pausing is the class, not a function type. You cant do Pausing.State();. the only time you use a . between two names is when you are referencing the script frrom another script, in which that case, you dont call the class, Pausing. You need to create a variable referencing that class (Pausing variableName;).
I also dont recommend declaring variables within a function. Thats considered to be local variables and its not smart to do. Its always best to make variables global unless you are certain you are only using them in the particular function they were declared in, otherwise youll get errors when trying to use them outside that function.