So when I read a monster that has 3/day each: Spell 1, Spell 2. I don't know what it means by the word "each"? Does it mean:

The monster can cast either Spell 1 or Spell 2 3 times a day or the monster can cast Spell 1 and Spell 2 3 times a day?

Each means that the 3/day applies separately to each spell.

Without the word "each" then the 3/day would apply across all the spells.

Thanks man!!

Also, most of the time the spells themselves have only a few attack options.  Those lists tend to be:

Problem solver, Problem Solver, problem solver, Defense, Offense,