How to get a players profile description?

There's no ROBLOX api for it, so you'd need to scrape the site. Since I've already written something like this before, here's an example in python.

#!/usr/bin/python

import sys
from termcolor import colored
from urllib2 import urlopen
from bs4 import BeautifulSoup as bs

userid = raw_input("User id: ")

if len(userid) > 0 and userid.isdigit(): 
    url = "https://www.roblox.com/users/{0}".format(userid)
    url = urlopen(url).read()

    if len(url) != 0:
        soup = bs(url, 'lxml')
        match = soup.find("span", {"class": "profile-about-content-text linkify"})
        print(match.text)
else:
    print colored("User-id invalid", 'red')

--[[
>
Welcome to the Roblox profile! This is where you can check out the newest items in the catalog, and get a jumpstart on exploring and building on our Imagination Platform. If you want news on updates to the Roblox platform, or great new experiences to play with friends, check out blog.roblox.com. Please note, this is an automated account. If you need to reach Roblox for any customer service needs find help at www.roblox.com/help
--]]