First: I recommend using a ledger or a trezor. From what I have used, I like these the best. Don't buy these on eBay! Make your own choice, but consider the following:
One hardware wallet will secure your crypto. When you set it up, you'll write down a list of words that you can use later to restore your device, or recover your funds on another device. It is important to keep this list safe. If someone gets these words, they can steal your coins. However, they are your only way of recovering your funds if you lose access to your original device.
So you have your hardware wallet. And you have your seed words. You're good to go, right? You load some coins, maybe you spend some, and you go on with your life. Then something happens.
You lose the device. Or, you flash a firmware update and need to restore. Or, someone steals your device. Maybe your dog eats it. You can order a replacement, and nervously wait for it to arrive... Or, you can find a software or web wallet to immediately restore. And hope you don't get hacked/swindled. But what happens if you made a mistake when you wrote down the initial seed phrase?
You lose everything.
One word out of order, or misspelled, and it's all gone.
There's two good ways of avoiding this.
The good way:
When you first get the device, set it up and either send a small test transaction or simply check the first receiving address (write it down). Immediately wipe and restore the device. If you get something like: "Error, invalid seed," this means you messed up. Start over (set up again as a new device) or try entering the words again. To be certain: check that the funds are there or that the receiving address matches.
The even better way:
Have twins! Order two of the same device. Set up the first device as new, and then restore the second device using the passphrase from the first. Now, you know you got the seed words 100% correct, AND you have a backup device. Hide it, lock it up in a vault, bury it, whatever. If something happens to one, you already have the other one ready to go!
For less than $100, I sleep a lot better at night after having twins. (Said no actual parent, ever!)