This is a short, lyrical piano piece by Franz Schubert, often performed as a standalone miniature. It is distinguished by its warm melodic lines and gentle harmonic progressions.
Focus on expressive legato phrasing and sensitive dynamic control.
Adagio (D.349) is rated Henle level 4 of 9 — intermediate repertoire, roughly ABRSM grades 5–6. In the RCM system it corresponds to about level 4.
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 Adagio (D.349) lasts about 6 minutes.
Adagio (D.349) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.