Originally from the opera 'Les contes d'Hoffmann', this is one of the most famous melodies in classical music. It is marked by its hypnotic, rocking motion and haunting vocal-like phrasing.
The main challenge is maintaining a consistent, liquid tone throughout the shifting hand positions.
Barcarolle, from Tales of Hoffmann 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 Barcarolle, from Tales of Hoffmann lasts about 4 minutes.
Barcarolle, from Tales of Hoffmann is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.