This Andante by Mozart is a substantial and expressive movement, often found within his piano sonatas. It showcases his mastery of melodic invention and harmonic grace.
Develop a warm, singing tone and pay close attention to the shaping of phrases and the balance between melody and accompaniment.
Andante in B-flat major is rated Henle level 4 of 9 — intermediate repertoire, roughly ABRSM grades 5–6. In the RCM system it corresponds to about level 6.
You should be comfortable at Henle level 4 — meaning you can already play level 3–4 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 Andante in B-flat major lasts about 3 minutes.
Andante in B-flat major is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.