Moving from black & white or a monochrome palette can be intimidating so here are some books about color that I recommend.
The first few are mostly about the history of color and pigments which, while maybe not adding so much to technical skills, can still be very inspiring and who doesn’t like fascinating stories such as the origin of “mummy,” a pigment made of…mummies, and the various ways yellow pigments can kill or make you ill. These are listed in the reading order I’d recommend:
The Secret Lives of Color by Kassia St. Clair
Color: A Natural History of the Palette by Victoria Finlay
Bright Earth: Art and the Invention of Color by Philip Ball
If you are more interested in the techniques of using color, here are some books to explore.
The New Munsell Student Color Set. The 2nd edition is shown here but there’s now a 4th edition in print (book title link). This is a workbook that helps train your eye to see slight variations in hue and value. I first used it many years ago but regularly return to it since the swatches are great for helping with color matching while mixing paint. Munsell also makes larger learning tools such as the Munsell Interactive Learning Kit. I dream of someday owning a copy of the Munsell Book of Color. Check out the Wikipedia entry for Albert Munsell for a bit more history.
Interaction of Color by Josef Albers. This is also available as an app which I highly recommend getting for your phone or tablet because you can do the exercises within the app. The book provides exercises also but it takes a bit more effort to complete them. Albers teaches more complex color theory than Munsell and I admit some were a bit difficult to fully grasp and integrate into my art practice. And here’s Wikipedia on Josef Albers for a historical perspective.
Color for Painters: A Guide to Traditions and Practice by Al Gury. Out of these three color theory books, Gury’s is the most straight forward how-to book. He touches on history of color usage but also offers demonstrations of various painting techniques.
There are many free online color theory & color history resources as well as color theory instructional videos on YouTube. I’ve also found a few color theory instructional videos on for-pay services such as Skillshare, Bluprint, Craftsy, etc.