Schubert's Adagio in G major is a charming and lyrical piano piece, notable for its simple yet expressive melody and gentle harmonic progressions.
Focus on creating a smooth and connected melodic line with careful pedaling.
Adagio in G major (D.178) is rated Henle level 3 of 9 — late beginner repertoire, roughly ABRSM grades 4–5. In the RCM system it corresponds to about level 3.
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 Adagio in G major (D.178) lasts about 5 minutes.
Adagio in G major (D.178) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.