فَاعِل: the noun functioning as the doer/subject of an action.
فِعْل: a verb expressing an action with tense.
صِفَة: here, a derived description capable of governing like a verb.
أُسْنِدَ إِلَيْهِ: attributed to it.
قَامَ بِهِ: the action proceeds from it.
وَقَعَ عَلَيْهِ: the action falls upon it.
These terms express the logic of the definition; memorizing a word-for-word translation alone is insufficient.