You posted in PSOC 1 forum, PSOC 1 does not have DMA, just PSOC 3/5.
DMA is a method, in today’s parts, using separate busses so that CPU intervention is
not required to transfer data from one peripheral to another, or I/O ports, etc.. It is
almost always faster than CPU directed transfers, so is capable of keeping up with
communication rates like SPI, UART...... It effectively gives you many more MIPs
in a machine, and depending on architecture runs concurrently with other CPU