Look at the image below:
This image is about weather forecast. It says about chance of rain during coming few hours of the day in the city. Look at the number 30% at 7 AM. It means that there is 30% chance of rain at that time. In other words, probability of rain at that time is 0.3. It gives you some idea but can you conclude anything from this? You can expect to have rain on 3 occasions out of 10 with similar conditions and forecast. Mind it, you expect only. You are not sure. In fact, you will get rain on other than 3 occasions out of 10 more frequently than 3. Probabilistic situation is like that. It deals with uncertainty.