Alberto Williams is a major figure in Argentine classical music, and this piece reflects his lyrical, post-romantic sensibilities. It explores a gentle, introspective melodic style characteristic of South American Romanticism.
The performer must use subtle rubato to breathe life into the nostalgic melodic phrases.
Comparable difficulty and character — good candidates for what to learn next.
Canción de Niño is rated Henle level 3 of 9 — late beginner repertoire, roughly ABRSM grades 4–5. In the RCM system it corresponds to about level 5.
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 Canción de Niño lasts about 3 minutes.
Canción de Niño is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.
Pieces at a comparable difficulty and character include 'O sole mio by Eduardo Di Capua, Believe Me, If All those Endearing Young Charms by Irish Folk Music, Belle of the Ball by Leroy Anderson — see the full similar-pieces list on this page.