Arduino for STM32

https://www.youtube.com/watch?v=zSYnSyf723g

I have a Nucleo F446RE and also a ledmatrix board HUB75..
and I want to do something like this youtube movie...

can somebody give some help... to start?

Have you visited adafruit web-site?

HUB75 isn't formally documented, it is reverse engineered
https://hackaday.com/tag/hub75/
https://hackaday.com/2020/05/09/reverse ... ed-panels/
https://hackaday.com/2015/01/05/rgb-led ... 2-and-dma/
https://01001000.xyz/2020-05-03-Rescuin ... ED-Matrix/

Most of LED panels are like multiple 74HC595 in series. Even signal names are similar (clock, strobe and output enable). Output of one color can be connected to an input of next color. If there is A,B,C,D or similar letters on a input/output connector, it means they are multiplexed. Most probably P-mosfet driving 1/4 of screen, or maybe even 1/8 or 1/16 with demultiplexer.

Using SPI library should be enough for a start (using just CLK and MOSI pin)
Check datasheet for chips that are driving leds, i don't think it can go over 20MHz at 3.3V

You can check if this library is compatible with you LED:
https://github.com/adafruit/Adafruit_NeoPixel/pull/206
I've added the STM32 support long time ago.