Luccicare means 'to sparkle' or 'to shine'. It's a beautiful and evocative verb that paints a vivid picture.
In the song, the lyric "Sono quattro settimane che ti vedo luccicare" (It's been four weeks that I've seen you sparkle/shine) suggests the person being observed has a radiant quality, perhaps due to happiness or a captivating presence. It's a more poetic choice than common verbs for 'seeing' or 'looking', making it stand out.
"Psicologia Sociale" is Zero Assoluto looking back on a summer romance that's already ending. The streets and songs from the radio are the same as always, but this time the singer feels everything differently because of one person who keeps showing up, making him laugh without even trying, and derailing his train of thought.
The title plays on the phrase "psicologia sociale" (social psychology) to describe the whole messy pattern of watching someone from a distance, second-guessing every move, and still ending up caught in it anyway. The repeated line "tutta roba da star male, male, male oppure no" ("all stuff that makes you feel bad, bad, bad, or not") captures that push and pull: is this heartbreak, or is it actually fine?
By the end, summer is over and so is whatever this was. The song doesn't resolve the question of whether he's better off or not, it just leaves it hanging, which is really the point: some endings are ambiguous, and that's okay.