Some different uses:
Allora = then, in hypothetical sentences like: if... then...
Allora = well, at the beginning of a sentences just as an introduction and keeping attention
"Allora, adesso vi racconterò di come io..."
"Well, now I will tell you how I..."
Allora = in that time/period
"Quando vivevo in Italia incontrai lei, fu allora che me ne innamorai"
"When I have been in Italy I meet her, it was in that time I have fallen in love with her"