I'll clear this up for you:

SS - Spell Speed
SS - Sacred Soil
SS - Stoneskin

Got it? Good. On a serious note though, it's all about context; if someone is claiming to have 31 SS on his robe, I doubt he's talking about Sacred Soils or Stoneskins. At the same time, if someone is telling the WHM to SS before Mountain Buster, it's not Sacred Soil.

Oh, and usually people use SKS and SPS for stats.