Caster Level

Many creatures are endowed with Numen, and spellcasting. But because of the complex system of noting down a myriad of useful spells, the DM often has to look down at a big list of spells when it comes to magical creatures. For this reason, creatures may come with a “Caster Level” on their stat sheet.
This Caster Level vaguely indicates at what magic level the creature usually is, providing a guideline for the DM to fill in spells they find useful, or to empower the DM to add spells as they become relevant.
It is simply a guideline for the DM to use, but some creatures may come with restriction on schools of magic, or they may already come with a small list of known spells.