This title likely refers to one of Bach's short pedagogical pieces, possibly from the 'Notebook for Anna Magdalena Bach' or an invention. These pieces are renowned for their clear contrapuntal textures and motivic development.
Focus on clean articulation and precise execution of the contrapuntal lines.
Beliebte kleine Stücke is rated Henle level 2 of 9 — beginner repertoire, roughly ABRSM grades 2–3. In the RCM system it corresponds to about level 3.
You should be comfortable at Henle level 2 — meaning you can already play level 1–2 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 Beliebte kleine Stücke lasts about 1.5 minutes.
Beliebte kleine Stücke is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.