This is a lyrical and expressive piece often found in orchestral suites or arrangements. It's distinguished by its soaring melody and rich harmonic language.
Focus on creating a warm, sustained tone and managing the legato phrasing.
Adagio molto in E-flat major is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7. In the RCM system it corresponds to about level 7.
You should be comfortable at Henle level 5 — meaning you can already play level 4–5 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 molto in E-flat major lasts about 5 minutes.
Adagio molto in E-flat major is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.