Hey there! I'm happy to help!
Edge cities are usually formed because land in the suburbs or on the outskirts of the city is cheaper (bid-rent curve), so they can make more a profit.
These businesses are normally connected the the CBD (central business district) so transportation to and from that area is still possible.
People that live in the suburbs or are visiting the main city have easy access to the edge city as you might not have to travel as far to these cities as the CBD (distance decay).
Edge cities can be a good thing because they allow for new businesses to thrive and they can increase economic activity and competition due to new construction, cheaper prices, new companies moving in, etc.
However, they can also be a detriment to the CBD because they might allow companies to relocate due to the cheaper land prices, they might take in the typical customers of the CBD companies, ultimately leading to the vacancy of the CBDs, which could be dangerous and create high-crime, unsanitary, or contaminated areas. It can also take attention away from significant or historical monuments and locations in the CBD.
Have a wonderful day and keep on learning! :D
