What Does "spells" Refer To In The Class Section Of The Help Page?

All of the others make sense, I just don't get what "spells" is meant to refer to.
Damage is self explanatory (even if it isn't always accurate since there's so much build variety)
Defense is a measurable amount of damage increase/decrease
Range is also self explanatory (archer has more range then warrior, obviously)
But I just don't understand what Spells is meant to mean. Is it stating the strength of the spells? Hopefully not, since Assassin and Archer (both 3/5 for spells) have much better spells than mage (5/5). Is it a statement about how powerful the spells are meant to be? Or how central they're meant to be to a classes playstyle? I'm very confused.

 

I am pretty sure spells refers to the diversity of spells or the overall strength of spells.

for example warrior's spells are mostly damage based with some other capabilities.

mage however has a more diverse set of spells that have a greater number of applications

 

Basically how good your spells are, or how much yo will be using them. Shaman and mage are both very spell based, while warrior is less so

 

Mage has arguably the best spellpool ingame. Heal is of course heal, teleport is an instant movement spell, and meteor has a total of 625% damage, making it the most damage-dealing spell ingame (note that Mage's base damage is low). Imagine Archer but with Mage's stats. It would be a bad class. If you just look at the spells as they are, Mage has the best spellpool (though Vanish is arguably the best spell and Assassin is a very good contender).