The available columns for any given table are fetched from a system table called "sys_tablecolumns". A specific table name is provided in the WHERE criteria to restrict the table from which the column information is fetched:

import cdata.googlespanner as mod
conn = mod.connect("ProjectId='project1';InstanceId='instance1';Database='db1';OAuthClientId='757060765381';OauthClientSecret='abc';")
cur = conn.cursor()
cmd = "SELECT * FROM sys_tablecolumns WHERE TableName = '[CData].[GoogleSpanner].Customer'"
cur.execute(cmd)
rs = cur.fetchall()
for row in rs:
	print(row)