This piece is a charming dance from a ballet by André Messager, known for his operettas and ballets in the late Romantic era. Its musical distinction lies in its melodic sweetness, flowing harmonies, and characteristic dance rhythms.
Cultivate a singing tone and a sensitive use of rubato.
Ballet d'Isoline is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7.
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.
Ballet d'Isoline is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.