VGA connectors have 15 pins, three of these are used for color data of red, blue and green. Based on this project, each color has a width of 8 bits. However if under the scheme of 8-bit color, each color will have 8 bits of data. (Upon further inspection, 8-bit color means 3 bits red, 3 bits green and 2 bits blue) How can you have multiple bits of data in one pin?
A VGA signal cable uses analog signals for R, G, and B. H-sync and V-sync are... digital sync pulses.. but the color channels need to be converted into a digital signal through a sampling process to be fed into an LCD.
Traditionally these signals were fed into a CRT with a red, green, and blue cathode ray, and so these signals were simply modulated into the beam intensity of each.
The VGA color signals are analog, between 0 and 0.7V. 8-bit resolution is just a limitation of implementation. Depending on your DAC, you could have more bits (e.g. 8 bits per color).
The VGA color signals are analog- 700mV for full brightness and 0mV for minimum.