The I65GV25_R2RDAC_01 specifies a 10-bit R2R DAC. At the output side a voltage-mode buffer is used to generate the output voltage and filter out the excess out of band noise.

Although the PSoC has some analog capability, [MiguelVP] uses a cheap R2R DAC and VGA connector to interface to the VGA monitor. You can get the same PSoC board the project uses for about $10.