Full list of all 56 Tales of Zestiria achievements. It takes around 100-120 hours to unlock all of the achievements in the base game on Windows.
The base game contains 50 achievements, and there is 1 DLC pack containing 6 achievements.
This is proof that you've equipped items that activate a Stack bonus skill. You can get Stack bonuses by equipping more than one copy of the same skill at once. The more copies of that skill you equip, the cooler your Stack bonus will be!