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.bingads as mod
conn = mod.connect("InitiateOAuth=GETANDREFRESH;AccountId=442311;CustomerId=5521444;DeveloperToken=11112332233;")
cur = conn.cursor()
cmd = "SELECT * FROM sys_tablecolumns WHERE TableName = 'AdGroups'"
cur.execute(cmd)
rs = cur.fetchall()
for row in rs:
	print(row)