Tails is a portable operating system that protects against surveillance and censorship. Tails gives you a secure computer anywhere. Just borrow a computer, turn it off and restart it with your Tails USB stick. Tails always starts from the same clean state and everything you do disappears automatically when you shut down Tails. It has amnesia. No log files. No web cache. No list of recent files accessed.
You can save some of your files and configuration in an encrypted Persistent Storage on the USB stick: your documents, your browser bookmarks, your emails, and even some additional software. The Persistent Storage is optional and you always decide what is persistent. Everything else is amnesic.
The large 32 GB USB flash drive uses the fastest version of USB, version 3.2. Tails only takes a small part of the 32 GB of space. There is plenty of space left for you to add your own Apps, photos, etc. Tails is based on Debian, so you have access to the Debian Package Repository, which contains tens of thousands of packages/apps, all free of charge, with open source licenses.
Everything you do on the Internet from Tails goes through the Tor network. Tor encrypts and anonymizes your connection by passing it through 3 relays. Relays are servers operated by different people and organizations around the world. This means that if you search for a car, you won't be seeing ads for cars later. Tor is also home to the "dark web", consisting of web sites that only exist inside of Tor.