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.sage50uk as mod
conn = mod.connect("URL=http://localhost:5493/sdata/accounts50/GCRM/{C4C863BE-B098-4A7D-A78B-D7A92B8ADB59};User=Manager;Password=xxxxxx;")
cur = conn.cursor()
cmd = "SELECT * FROM sys_tablecolumns WHERE TableName = 'TradingAccounts'"
cur.execute(cmd)
rs = cur.fetchall()
for row in rs:
	print(row)