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.servicenow as mod
conn = mod.connect("InitiateOAuth=GETANDREFRESH;OAuthClientId=MyClientId;OAuthClientSecret=MyClientSecret;User=MyUser;Password=MyPassword;Url=https://MyInstance12345.service-now.com/;")
cur = conn.cursor()
cmd = "SELECT * FROM sys_tablecolumns WHERE TableName = 'incident'"
cur.execute(cmd)
rs = cur.fetchall()
for row in rs:
	print(row)