New to Arduino Uno

Hi Everyone! I am a student of high school physics. I am interested in physics and engineering. I want to start making projects because I think they are very cool. So where do I start from basics I guess. Should I get a book or something?
I want to know like Where does this Uno stand in the world of engineering, how does it work and everything. What is the power of this small piece?
I have a goal too. I want to make a robot which can deep learn and tell and identify handwritten numbers on a paper and also to make my own mechanical arm and things like that. robot cars which can sense obstacles and turn automatically.
I want to know if Uno is a small computer then what about using the actual pc to run devices,etc

Buy a Arduino Uno, install the Arduino IDE and run the Blink sketch and try to make it blink faster and slower.
If you can do that then you have the whole process from source code to Arduino board working and after that you can decide if you like it and if you want to read books or Youtube tutorials.

The Arduino Uno is good for buttons and leds and clocks, but there are many other boards and also Arduino-"compatible" boards, such as a ESP32 with Wifi.

That takes a lot of computing power so the UNO family isnt IMHO a great match.

Much better suited to using arduino devices.

A microcontroller like the arduino family is not the same as a microcomputer.

will give you an idea of what they can do.

Have you done any programming yet?

If not that's OK because with the Arduino it's pretty easy to get started learning programming. You also need to know (or learn) a little about electronics and you may already know some of that from physics.

It's a microcontroller which is like a CPU chip with some special features like an analog-to-digital converter and built-in flash memory. And, it's doesn't have the address & data bus like a microprocessor (CPU) that's buit-into a computer,

It's not a complete computer... There is no operating system, no file system, and no standard keyboard/mouse or display connections.

A microcontroller is more suited for "embedded systems" working with special/custom hardware, like driving servo motors, or if you want to build an alarm system with several sensors and a couple of alarm-outputs, etc... Something with one specific application where you don't need a keyboard or video display or a hard drive. Modern cars may have multiple microcontrollers for various specialized functions.

The main advantage of the Arduino over a "random" microcontroller chip is that it's mounted on a ready-to-use board and it has a bootloader & USB so you can plug it into a USB port and start programming it.

A regular-bare microcontroller requires a separate development board and usually a separate programmer. Then you need to make a custom PC board for your product or project.

There are also "single board computers" such as the Raspberry Pi. These do have an operating system and ports for a keyboard, mouse, display, and file storage. These are more powerful than the Arduino but the Arduino is usually better if you have "non-computer" hardware like switches, relays, motors, LEDs, etc.

You can communicate with the Arduino via USB, or over Ethernet or Bluetooth, etc., if you add some additional hardware. But, it doesn't easily "integrate" with the computer like a normal peripheral with a specific driver. And, this usually involves writing a computer program as well as an Arduino sketch.

What is the history of arduino? Where does it all start? I mean from scratch.

The attached Experiment Sheets might be helpful for you to learn the the Programming and Interfacing of UNO. For more materials, you may visit this Google Class (Class code: shqmtej).
Expt-1-2-3-4.pdf (941.7 KB)