Pruning should be done before the tree starts to bud out in the Spring. To encourage new growth, this is the best time. For shaping, anytime the plant is dormant, has lost its leaves, will work.
If you wanted to prune a tree, you will need a Class 1 fulcrum.
Your English is incorrect, should read, "How do you prune an olive tree?"
You can prune it but the symmetrical shape that makes it attractive will be wrecked. If you do prune only tip prune.
Prune it after leaf fall. It depends why you want to prune it. Trees dont usually need pruned as it spoils their natural shape. If it has become too large for its space then cut it back but remember pruning causes more growth.
prune them
winter
During the Winter.
Jack Walker
I have no idea.=D
early spring
If you mean a beech hedge then August in the Northern Hemispere is best. If it is a tree there should be no need to prune it other than to shape it and you can do this at any time. If you do that too often it will become a hedge and be best done in August.
Prune it during the growing season. but dont cut off any fruiting wood unless you have to.