Joseph O'Kelly was an Irish-born composer active in Paris, and his 'Bertha' is a characteristic salon piece. It centers on a lyrical melody supported by warm, resonant piano textures.
Prioritize the cantabile playing style by balancing the melody against the accompaniment.
Comparable difficulty and character — good candidates for what to learn next.
Bertha is rated Henle level 3 of 9 — late beginner repertoire, roughly ABRSM grades 4–5. In the RCM system it corresponds to about level 3.
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 Bertha lasts about 3 minutes.
Bertha 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 Berceuse by Joseph O'Kelly, 'O sole mio by Eduardo Di Capua, Believe Me, If All those Endearing Young Charms by Irish Folk Music — see the full similar-pieces list on this page.