Mungbean yellow mosaic virus is a tiny creature that can be harmful to plants called mungbeans. This virus is so small that you wouldn't be able to see it with your own eyes because it is a type of microbe.
When the virus infects the mungbean plant, it can cause the leaves to turn yellow, making it unable to grow properly. This is because the virus makes the plant sick and weak, just like how you might feel when you get a cold or the flu.
Just like how you can catch a cold by being around someone who has it, the virus can also spread from plant to plant through tiny bugs called whiteflies. These bugs can carry the virus from a sick plant to a healthy one, and infect the new plant too.
There are ways to prevent your mungbean plants from getting infected by this virus. One way is to make sure that your plants are healthy and strong so that they are less likely to get sick. Another way is to keep an eye out for any signs of the virus and quickly get rid of any sick plants to stop the virus from spreading to other plants.