Hi Prabhakaran!
Feel free to check out this YouTube channel started by a PM on our team: https://www.youtube.com/channel/UCPncyTU_HUNNcJS3Kol2n0w. I don't believe there are any Office Scripts books available yet, though hopefully that will change someday :)
Thanks for this question - we're glad and honored that you're trying out our tool!
-Nancy from the Office Scripts team