These are a collection of short lyrical pieces by Widor, often focusing on expressive melody and refined harmony. They are designed to be beautiful miniatures, showcasing melodic invention.
Focus on developing a singing tone and sensitive phrasing.
40 Mélodies 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.
40 Mélodies is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.