Auto backups history

Dears, please share with us strong details about :
1- Number of Backups , ERP-Next website >> setup >> System Settings >> Number of Backups >> 5
its meaning will delete the older of 5 backups?
2- How to keep history for some days.
3- Is the mentioned setup working with manual and auto backups?
4- From your code, the old backups will remove daily, whether the keep_backup_for_hours option is not specified, please more details about keep_backup_for_hours option.

   def scheduled_backup(older_than=6, ignore_files=False, backup_path_db=None, backup_path_files=None, backup_path_private_files=None, force=False):
	"""this function is called from scheduler
		deletes backups older than 7 days
		takes backup"""
	odb = new_backup(older_than, ignore_files, backup_path_db=backup_path_db, backup_path_files=backup_path_files, force=force)
	return odb

def new_backup(older_than=6, ignore_files=False, backup_path_db=None, backup_path_files=None, backup_path_private_files=None, force=False):
	delete_temp_backups(older_than = frappe.conf.keep_backups_for_hours or 24)
	odb = BackupGenerator(frappe.conf.db_name, frappe.conf.db_name,\
						  frappe.conf.db_password,
						  backup_path_db=backup_path_db, backup_path_files=backup_path_files,
						  backup_path_private_files=backup_path_private_files,
						  db_host = frappe.db.host)
	odb.get_backup(older_than, ignore_files, force=force)
	return odb

Thanks.

Updates !!