Photography is, the longer the exposure time, the better? How does the long exposure time affect the photos?

Exposure is the time when the shutter is open. Exposure time depends on the shooting environment. If it is sunny every day, normal exposure is enough. If the exposure time is longer, only white will be taken. But when you don't want to turn on the flash when shooting at night, you can slow down the shutter appropriately (extend the exposure time).