It's a human readable backup of your private keys making you to be able to restore access to your funds if your wallet app is damaged, or you simply want to use a different wallet interface.
When it comes to using a wallet, it is always advised that we choose a very good wallet with effective security. In as much as we always encourage the hardware form of non custodial wallet, the price happens to be a big deal, though there are few other options, like software mobile wallets that can be installed on our mobile phones, and few of them have similar features like good security and Open source AFAIK. And importation using our phrase makes it easier to recover a wallet, rather than creating a fresh one.
I usually recommend hardware wallet when the person is aiming to hold a significant amount of money in his portfolio so as to optimize his security for better user experience with limited chances of getting scammed. But if his intentions for the time being is a hold a small amount of coin then mobile wallet is the best option for him, and for optimum security he can choose to make use of a separate device which should be an airgapped device for the purpose of his Bitcoin wallet only. It's more cheaper than buying a hardware wallet and more secure than using your regular mobile phones.