Restoring a snapshot is very easy. A snapshot can be restored to other clusters to provide the cluster in which you are restoring it its compatible version.
You cannot restore a snapshot to a lower version of Elasticsearch.
While restoring snapshots, if the index does not already exist, a new index will be created with same index name and all the mappings for that index that were there before creating the snapshot. If the index already exists, then it must be in the closed state and must have the same number of shards as the index snapshot. The restore operation automatically opens the indexes after successful completion.
To take an example of restoring a snapshot from a repository