These are transcriptions or arrangements of J.S. Bach's preludes for piano. They offer pianists access to the master's contrapuntal genius and harmonic ingenuity in a familiar format.
Focus on achieving clear and balanced contrapuntal lines with appropriate articulation.
10 Préludes de J.S. Bach is rated Henle level 3 of 9 — late beginner repertoire, roughly ABRSM grades 4–5. In the RCM system it corresponds to about level 6.
You should be comfortable at Henle level 3 — meaning you can already play level 2–3 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 10 Préludes de J.S. Bach lasts about 15 minutes.
10 Préludes de J.S. Bach is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.