Can u help me about how the spi is working.
I want to use multiple 74hc595 so can anyone help me out this
Welcome to the forum
Have you searched the forum for 74HC590 74HC595 SPI ?
I suppose you must have looked here:
https://www.arduino.cc/reference/en/language/functions/communication/spi/
Did you have any specific questions?
Usually multiple 74HC595 shift registers are daisy chained.
Do you want them to act together as one long shift register (daisy-chained) or do you want them to act as separate 8-bit devices?
Also why do you want to use SPI? Of course you can, but if you are doing something slow like controlling relays or LEDs, you don't need it.
Yes i want a long shift register to control leds 8x8.
Why don't you just use a one MAX7219 chip?
Beat me to it! 
MAXes rule! 
Nah. TM163x and HT16K33 rule.
Problem with TM163x is they do not chain. 
Except via I2C addresses... the libraries I have used didn't support it completely but it was easy to extend the class to do that. Anyway, OP needs 8x8 matrix. I wonder if OP has considered the 8 current limiting resistors?
To daisy-chain:
Arduino SCLK goes to SRCK on all registers
Arduino MOSI goes to SER on the first register
QH' (QH prime) of each register goes to SER of the next register.
The TM1637 uses an interface that slightly resembles I²C, but is not I²C and does not support individual addresses.
Are there other versions of the "TM163x" beyond the pseudo-SPI TM1638 which does not chain either?
Oh, right. It's the HT16K33 that is genuine I2C. You're right, those don't chain. Yes, there are a handful of lesser known TM163x, like TM1636 and a few more. Those would be mostly out of production now. Yes, the MAX has that advantage. I like the TM and the HT because they are specified for 3.3V operation (you have to do some real digging in the data sheets to find it, though).
Reminds me - we don't know yet what processor is involved.
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