Explicit wait is a smarter then implicit wait. With explicit wait we can tell WebDriver to wait for an element based on various conditions.
In the example below, one quote will be displayed, and you want WebDriver to wait until the text is present on this element. But the problem is quote will be displayed between 5 to 60 seconds.
In this situation we can use ExplicitWait to instruct WebDriver to wait maximum 120 seconds but if found early proceed.
In following example, we will need to click on a button. But button will be present in web page between 10 - 3o seconds. We can use ExplicitWait here to tell webdriver to wait for button to be present with maximum of 60 seconds. In this case again, webdriver will wait max 60 seconds but, if button found before webdriver will continue to next step.