Francisco Tárrega's "6 Preludios" are a collection of short, evocative pieces that showcase his mastery of the Romantic guitar idiom, often translated effectively to the piano. They are characterized by their melodic beauty, harmonic richness, and Spanish flavor.
Focus on creating a rich, resonant tone and executing the nuanced articulation required for the melodic lines.
6 Preludios is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7. In the RCM system it corresponds to about level 8.
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.
6 Preludios is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.