Explanation:

Box 1, Box 2: TableBatchOperation
Create the batch operation.
TableBatchOperation op = new TableBatchOperation();
Box 3: ExecuteBatch
/ Execute the batch operation.
table.ExecuteBatch(op);
Note: You can insert a batch of entities into a table in one write operation. Some other notes on batch operations:
You can perform updates, deletes, and inserts in the same single batch operation.
A single batch operation can include up to 100 entities.
All entities in a single batch operation must have the same partition key.
While it is possible to perform a query as a batch operation, it must be the only operation in the batch.
References:
https://docs.microsoft.com/en-us/azure/cosmos-db/table-storage-how-to-use-dotnet