This aria by J.S. Bach is a deeply emotional and introspective setting of a penitential text. Its beautiful, flowing melody and rich harmonic language are characteristic of Bach's mastery of the aria form.
Requires a highly developed sense of legato and expressive phrasing, with precise pedaling.
Ach Gott, tu dich erbarmen (BWV 1109) is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7. In the RCM system it corresponds to about level 8.
You should be comfortable at Henle level 5 — meaning you can already play level 4–5 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of Ach Gott, tu dich erbarmen (BWV 1109) lasts about 4 minutes.
Ach Gott, tu dich erbarmen (BWV 1109) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.