It's a bad address, cause he's giving out the LAN address asigned by the router.
For you to be able to use it, you would need to be in his lan or in an VPN to his lan.
To real test what you got externaly, you need to give the external (to world) ip which is given by your own router admin panel, and/or websites like whatismyip.com.
then you need to do Nat from your external Ip to your local ip, specifying so in the router.
Or else, just share the website in a zip, and save time to do stuff like eat an ice cream, drink a soda/beer and have fun.