Flipping describes the activity of usually short term investments with the goal of reaching quick profits. For example, buying newly issued tokens in an ICO, then quickly selling (dumping) them, once they get listed on a public exchange.
In order to be successful at flipping, you need to act quick and get access to the right information as TIMING is everything in this strategy.
Flipping is a popular strategy in basically any business area ... real estate, buying established companies, buying web properties ... it's all about buying at the right time for the right price, then re-selling later on for a higher price.