def describe_vault(accountId=None, vaultName=None):
    """
    This operation returns information about a vault, including the vault's Amazon Resource Name (ARN), the date the vault was created, the number of archives it contains, and the total size of all the archives in the vault. The number of archives and their total size are as of the last inventory generation. This means that if you add or remove an archive from a vault, and then immediately use Describe Vault, the change in contents will not be immediately reflected. If you want to retrieve the latest inventory of the vault, use  InitiateJob . Amazon Glacier generates vault inventories approximately daily. For more information, see Downloading a Vault Inventory in Amazon Glacier .
    An AWS account has full permission to perform all operations (actions). However, AWS Identity and Access Management (IAM) users don't have any permissions by default. You must grant them explicit permission to perform specific actions. For more information, see Access Control Using AWS Identity and Access Management (IAM) .
    For conceptual information and underlying REST API, see Retrieving Vault Metadata in Amazon Glacier and Describe Vault in the Amazon Glacier Developer Guide .
    See also: AWS API Documentation
    
    Examples
    The example retrieves data about a vault named my-vault.
    Expected Output:
    
    :example: response = client.describe_vault(
        vaultName='string'
    )
    
    
    :type accountId: string
    :param accountId: The AccountId value is the AWS account ID of the account that owns the vault. You can either specify an AWS account ID or optionally a single '- ' (hyphen), in which case Amazon Glacier uses the AWS account ID associated with the credentials used to sign the request. If you use an account ID, do not include any hyphens ('-') in the ID.
            Note: this parameter is set to '-' bydefault if no value is not specified.
            

    :type vaultName: string
    :param vaultName: [REQUIRED]
            The name of the vault.
            

    :rtype: dict
    :return: {
        'VaultARN': 'string',
        'VaultName': 'string',
        'CreationDate': 'string',
        'LastInventoryDate': 'string',
        'NumberOfArchives': 123,
        'SizeInBytes': 123
    }
    
    
    """
    pass
