The piano is a keyboard instrument that produces sound when pressed on the keys. Most modern pianos have a row of 88 black and white keys: 52 white keys for the notes of the C major scale (C, D, E, F, G, A, and B) and 36 shorter black keys raised above the white keys and set further back, for sharps and flats.
Major scales are the most important piano scales: firstly, because they are very common and, secondly, because they are fundamental to understanding keys. Major scales are the most common and useful to learn first on piano. Start with C Major as it has no sharps or flats, then G, D, and A.