Smart goals are like any other goals in google analytics, but they are basically created to view activity from google Adwords. Before using smart goals you have to follow certain steps meet few prerequisites.
You have to link your AdWords account with analytics
Before you set up smart goals, the linked AdWords account must have sent a minimum of 500 clicks to the Analytics view in the last 30 days.
Note: if the number of clicks drops below 250 within 30 days, smart goals will deactivate until it rises again to 500
The reporting view should not exceed 10 million sessions in 30 days
The data sharing settings Google products and services must be turned on for your analytics account.