It’s a little confusing. Amazon makes several devices.
This is a Kindle Paperwhite eReader. You can’t do anything on it except read books. I have one of these and love it. I do most of my reading on it. The battery life is amazing. It lasts for more than a month.
Here is an Amazon Fire Tablet. It’s cheap and supposedly easy to use. On this device, you can do a few things on the internet, but it does not give a wonderful experience of the internet. You can also read books, because you can get a Kindle app. It’s battery will only last about half a day of continuous use.
Now, because Amazon makes a Kindle app, you can download the app to your phone or your computer or any tablet. I have a Samsung tablet. It’s really old, but I still use it. Here is a similar tablet. You could put the Kindle app on this tablet and read books on it.
I prefer to read on the Kindle Paperwhite. It’s small. I can hold it in one hand.
You should be aware that when you buy ebooks from Amazon, right when you buy it, it downloads to the place where you send it. After a time – I have no idea how long – it goes to the cloud. The books are still available. You have to go to the Amazon website and access your account to download the book again.