Spiffero literally means 'draft' or 'breeze', often referring to a cold current of air coming through a crack.
In Ligabue's song, he uses it metaphorically in the line "C'è uno spiffero nell'anima" (There's a draft in the soul). This evokes a sense of vulnerability, a subtle but persistent discomfort or weakness that makes one susceptible to emotional 'illness', as he continues with "Ci si ammala facilmente quando c'è corrente" (One gets sick easily when there's a current). It's a unique and evocative image for emotional fragility.
Ligabue's "Essere Umano" is a rock anthem about the messy, contradictory, and brilliant business of being human. It's not a story with a beginning and an end, but a list of all the things we are, often at the same time. He kicks off with a reference to Adam and Eve, saying that being human is to "Cogliere la prima mela e tutti gli altri guai" (To pick the first apple and all the other troubles). From there, he lists our conflicting impulses: we try to outsmart fate, we shine without knowing it, and we can even "Piangere e uccidere ma nel vestito buono" (Cry and kill but in the good suit).
The chorus drives this point home with a series of powerful opposites. Life, he says, is a constant switch between being "Un giorno chiodo / Un giorno martello" (One day a nail / One day a hammer) or "Un giorno roccia / Un giorno cristallo" (One day rock / One day crystal). One day you're strong, the next you're fragile. One day you're the hero, the next you're the fool. The song argues that this constant change and internal conflict isn't a flaw; it's just the definition of being human.