It's a promo code for startup businesses. it's likely not carded, although google can shut you down for doing things you shouldn't be doing with it. Also, you will need a cc or VCC to use it I believe.
Edit - This is outdated, hence the promo codes don't work, but you get the idea.
http://www.earngurus.com/how-to-get-unlimited-500-google-cloud-coupons/