This 'Ariette' by Mozart is a delightful miniature, likely presenting a graceful theme with several inventive variations. It showcases Mozart's mastery of melody and harmonic color in a concise form.
Focus on a refined touch and precise articulation to highlight the delicate melodic contours.
Ariette (K.308) is rated Henle level 4 of 9 — intermediate repertoire, roughly ABRSM grades 5–6. In the RCM system it corresponds to about level 6.
You should be comfortable at Henle level 4 — meaning you can already play level 3–4 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 Ariette (K.308) lasts about 4 minutes.
Ariette (K.308) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.