question about certain pins on the Arduino

I'm new to Arduino and the Atmega328.
I am using an LCD from Adafruit and I noticed that in the sketch that I can change pins around for SID, SCLK, CS, and Reset. The LCD will run on any of the digital pins of my choosing.

I'm used to programming the Attiny85 without the Arduino IDE and just using C.
Why is it that the digital pins on the Arduino can handle any of the options such as SCLK, CS, Reset, etc?
I figured that you would have to use a specific pin on the Arduino for one of those options.
For example, there is only one Reset pin on the Attiny85. Is it because the digital pins can act as any of those options?
I originally figured I could only use 1 or 2 specific pins on the board for lets say CS(chip select?) or Reset.
I didn't know I could use any of the digital pins for those.

I'm assuming that the actual pins on the Atmega microcontroller connect to more than one of the board pins?

So if I was using my oled that uses s2i, can I use the Arduino IDE to program any of the digital pins for the MISO and MOSI? Or would I only be able to use the Arduino board pins of 11 and 12 on my Uno?
I'm looking at the pinout and it says only 11 and 12 handle MISO and MOSI.

Sorry for the silly question. I'm just confused.

The SPI library only works with the hardware SPI pins. The SPI interface is very much like talking to two shift registers: one doing output and one doing input. The SPI interface uses one clock for both directions and sends data out through MOSI at the same time it is reading data in through MISO.

If you don't need to Output and Input at the same time you can use the shiftOut() or shiftIn() functions to talk to an SPI device just like talking to a shift register. You will need a data pin (output or input), a clock pin, and a latch (or Chip Select) pin.

thank you