What is Upbit app?

Can you please elaborate on what the Upbit app is and what it offers to users in the cryptocurrency and finance world? Is it a trading platform, a wallet service, or something else entirely? How does it compare to other similar platforms in terms of security, fees, and the range of cryptocurrencies available? Is it user-friendly for both beginners and experienced traders? And finally, what are some of the key features and benefits of using the Upbit app?