What is the rule about subjects joined by and.?

The subjects joined by "and" are "compound " which would mean that they are made by 2 or more parts. Let´s see some examples;

- Bananas AND apples
- Dogs AND cats.

It might be added that sometimes compound nouns might function as compound subjects, such as;
- The girl and the boy.  
Two nouns conformed a (compound) subject. 

The subject has to be plural and it also has a requirement of a plural verb.