Add +X is a short handle used to convey that your attribute used is temporarily increased for this task (independently from the task type).

Clarifications:

• “Add +1.” should be interpreted as: “During this task you get +1 to the matching attribute.”
• “Add +1 to the next task this round performed by any character” should be interpreted as: “During the next task this round the performing character gets +1 to their matching attribute.”
• Adding +X to a Change Location action has no effect.