The Acacia family are mostly evergreen.
From the blossom of an Acacia tree.
Your English is incorrect, should read, "How do you prune an olive tree?"
They like acacia tree because of their leaves and they eat the leaves to survive
Buona acacia! in Italian is "Good acacia tree!" in English.
The Umbrella Acacia Tree
You can prune it but the symmetrical shape that makes it attractive will be wrecked. If you do prune only tip prune.