FPGAs can be seen as a bridge between the domains of hardware and software as their hardware operation can be reprogrammed using code, giving developers unprecedented flexibility. In advanced products that Antmicro helps its customers build, this flexibility to process parallel data often needs to be complemented with a more standard, sequential processing capability provided by a CPU, which can run control software and interface with the user or other devices.
article: https://antmicro.com/blog/2020/05/multicore-vex-in-litex/