The SPI function and UART function are sharing the same hardware pins.
The only difference is the configuration of the ****.

SPI uses synchronous **** with clock support.

The interface provides a transparent channel, which can help you
directly to send/receive ASCI I (hex coding) data and it always uses
the full-duplex ****.

In the current scope picture, SPI  is used with 8-bits per frame

The structure of the transparent channel is the following:

More informations about you will find in the ATC guide.