It is very risky indeed. The basic concept is that you make a bet on whether an asset will go up or down past a certain value, and - as opposed to regular trading, where you can manage your risks and fine-tune your trading process - the outcome is either "you were right" or "you were wrong", meaning you either get the specified payout, or you get nothing at all.
And what adds even more risk is that this structure means it is not in the interest of the broker for you to win, so there are a lot more frauds among binary option brokers than among regular ones.