The Aramaic word aru is an exclamatory particle meaning 'behold!' or 'lo!', used to draw attention to something remarkable or significant. It appears in the Aramaic sections of Daniel, functioning similarly to the Hebrew hinneh.
Exclamatory words like aru and hinneh serve a crucial rhetorical purpose in Scripture — they arrest the reader's attention, signaling that something theologically weighty is about to be revealed. In Daniel's Aramaic visions and decrees, this word introduces divine acts and royal proclamations, reminding us that when God acts, the appropriate response is reverential attention.