Definition of risk/reward
Literally, "risk-reward". If you want a reward, you have to take a risk. This is often the case in poker. The best example of the risk/reward concept is bluffing. When we bluff, we take a risk. If we bet 100??? on the river in a bluff, we are risking 100???. If our opponent calls our bluff, we lose 100???. But if he folds, we win a pot that we would not have won otherwise.
Calculate your risk/reward ratio
When we take a risk to get a reward, we want the risk/reward ratio to be good. To use the bluffing example we mentioned earlier, if we bet 100??? in a bluff to win a pot of 5???, that's an inordinate risk for a minimal reward. On the other hand, if we bet 100??? in a pot of 2500??? in bluffing, our bet will not discourage anyone from calling. The risk our opponent will take is not great enough to discourage him from calling the bet. It is usually necessary to select a good risk/reward ratio. If the reward is very large and the risk is acceptable, it is worth it. But if the risk is too great for the reward or the reward is too risky for the risk, you should pass.