artha 日迦他 (迦 being an error for 遏); affair, concern, matter; action, practice; phenomena; to serve. It is 'practice' or the thing, affair, matter, in contrast with 理 theory, or the underlying principle.

A Dictionary of Chinese Buddhist Terms, William Edward Soothill and Lewis Hodous

梵語 artha。指因緣生之一切有為法，即宇宙間千差萬別之現象。與平等門之「理」相對。僧肇之寶藏論（大四五‧一四三下）：「理合萬德，事出千巧；事雖無窮，理終一道。」〔俱舍論卷二十五、華嚴五教止觀、摩訶止觀卷一上〕（參閱「事理」3043）

佛光電子大辭典

p3039

事 [py] shì [wg] shih [ko] 사 sa [ja] ジ ji ||| (1) An affair, a matter, an undertaking, business. Matter, affair, manifest phenomena (vastu); concrete. (2) Distinct phenomenon. Individuality. Differentiated. (3) Function, activity, motion (kriyā). (4) Thing, object, body (dravya). (5) Realm, state, condition, scene.(6) In Huayan teaching, one of the four dharmadhātu, that of individual phenomena, mentioned in contrast to the realm of undifferentiated principle 理.

[Dictionary References] Naka565d [Credit] cmuller(entry) cwittern(py)

凡是因緣所生之法都叫做事，離因緣造作之法則叫做理.

陳義孝編, 竺摩法師鑑定, 《佛學常見辭彙》