spell damage phasing

Someone can tell me in other words what the phrase "spell damage phasing" means? Thank you in advance who tries to answer me

Not sure what you're talking about here. "spell damage" and "phasing" are two completely separate, unrelated things.

While mentioning the context it's coming up in would help, I think the short answer is:

"spell damage phasing" is a phrase without meaning.

"Phasing" is the state of being able to move around without colliding with enemies or some obstacles, like Ice Prisons.

I imagine this came up from looking up something with "Chance to Suppress Spell Damage" and "Phasing", such as Quartz Flasks, the Raider Ascendency "Quartz Infusion", or the Scion Ascendency "Raider".

In which case, the other half of the phrase would be "Chance to Suppress Spell Damage". You take 50% less damage from hits/ailments from suppressed spells.

So the writing on the quartz flask indicates not 1 but 2 mods, "10% chance to suppress spell damage" + "phasing". Now that you’ve told me, it’s almost obvious... Thank you very much!

Hover over the flask and hold down the ALT key, you will see that there are 2 different lines easier that way.

The fact is that if one assumes that it is a unique mod does not even think about using the ALT key

Using the ALT key works on all of your equipment.
Don't assume anything in PoE :)