What are the prerequisites to start with Raspberry Pi ?

A Raspberry Pie?

SCNR 😂

Besides of that, I would say: A basic understanding of Linux, and the most important part: an Idea what you want to do with it

$20 and access to google.

1x raspberry pi
1x USB keyboard (first use to get shh running)

A fair Understanding of Linux terminal commands and then its all up to you what you do from there.

Apart from the obvious Raspberry Pi, you will want to have a USB keyboard and mouse and a HDMI monitor to get started. If you haven't already, get a microSD card and an adapter and install Raspbian on it (it's a GNU/Linux distro for intro to Raspberry Pi. You can also try NOOBS from their website, which, if I remember correctly, will help you set up said Raspbian).

Then, you'll want to figure out how to use it. It does have a GUI, so you're ok there, but it's necessary to learn how to use the terminal, as that's where all the fun happens.

Next, you simply need a project idea, which you can find on Instructables or other websites. Keep in mind that the Raspberry Pi comes with no accessories usually - no temperature sensors, no cameras, no nothing. It's just a mini-PC.

Go wild.