Mozart's sonatina movements are excellent examples of Classical era piano writing, characterized by their clarity, grace, and balanced phrasing. They provide accessible yet musically rewarding material for developing pianists.
Strive for a light touch and precise articulation, especially in the Alberti bass accompaniments and melodic lines.
Ausgewählte Sonatinen-Sätze is rated Henle level 3 of 9 — late beginner repertoire, roughly ABRSM grades 4–5. In the RCM system it corresponds to about level 4.
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.
Ausgewählte Sonatinen-Sätze is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.