Monochromatic
Monochromatic colors are varying tints and shades of one hue. The paint swatch above shows different tints of red, meaning they added white, if you add black it would be a shade.
My Olio board I used red. I have pillows with reds and pink, and my pictures on the wall have reds and pinks in them. In a monochromatic room you can also add neutral colors so it doesn't look like too much of one color. I add a grey couch and some pillow. Making a room Monochromatic makes the room calming. Everything just works well together.
Analogous
Analogous colors are the colors that are right next to each other on the color wheel like, in the picture above they are showing, Blue-green, green, and yellow-green, as analogous colors.
In my analogous Olio Board, i did what the color wheel shows above, I did yellow-green, Green, and Blue-green. I added some neutral colors with the carpet, grey and white and black to make it look not so "one color."
Split-Complementary
The split complementary scheme is a variation of the standard complementary scheme. It uses a color and the two colors adjacent to its complementary. 
For example; on the color wheel above Reds compliment is green, but a split compliment would be the two colors on each side of Reds compliment, that would make reds split compliments Blue-green, and yellow-green.
Triadic
Triadic color schemes are three colors that are equal distance from each other on the color wheel. Like the primary colors Red, Blue and Yellow. They are all equal distance apart from each other.
