Apply / Remove

Apply grants content to the Player character. The editor names it after what you are granting — Apply a Feat or Condition, Learn a Spell, Gain an Item — but it is all one effect.
Remove takes it away again, and is called Remove whatever the content is.

When an Apply effect is triggered, any effects provided by the applied content are recursively applied as well.

Items

Gaining an Item puts a Weapon, Armor, Consumable, or Misc entry straight into the character's inventory, exactly as if the Player had picked it up.

Stacking and Repeatability

If the target Feat or Condition supports stacking or ranks, and the character already has an instance of it, the Apply effect will advance it to the next rank or add a new stack.
The effects associated with the new rank or stack are applied automatically.

If the target does not support stacking and the character already has it, the effect has no additional impact.

Reversibility

When an Apply effect is reverted (e.g. by unequipping the item or removing the class that granted it), the applied content is removed from the character, and all of its associated effects are cleanly reverted.

For stackable content, reverting removes one stack or rank. If multiple stacks remain, the character keeps the content at the reduced level with the corresponding effects still active.