These are simplified arrangements of Bach's inventions, designed for easier access to contrapuntal textures. They introduce fundamental principles of voice leading and harmonic progression.
Developing independent control of each hand to clearly delineate melodic lines is crucial.
23 Pezzi facili is rated Henle level 1 of 9 — beginner repertoire, roughly ABRSM grades 1–2. In the RCM system it corresponds to about level 2.
You should be comfortable at Henle level 1. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
23 Pezzi facili is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.