In music, tonality is the way a piece is organised around one central note — its key. When a song is 'in C major', C is home: the tune keeps pulling back to it, and the chords are built to make you feel that pull. That whole system, and the particular colour a given key gives a piece, is its tonality. Musicians also use the word for the bigger idea: music that works this way is 'tonal', and music written on purpose without a home note is 'atonal'. So when a critic writes 'the piece abandons tonality halfway through', they mean the sense of home disappears. Outside music the word gets borrowed for colour, especially by painters, photographers and designers — 'the warm tonality of the photograph' means the overall range and feel of its tones. That use is common in art writing and rare in speech. Careful with one thing: in ordinary English, 'tone' can also mean the feeling in someone's voice or writing, but 'tonality' is not usually used that way. For that you say 'tone'.