John Keeler’s great book Understanding NMR Spectroscopy (2010)(Amazon), which he amazingly makes mostly available on line as PDFs: http://www-keeler.ch.cam.ac.uk. That’s a really good place to start.
For a more in-depth treatment, Spin Dynamics (2008) by Levitt (Amazon)
More tailored to application of NMR to proteins, in solution:
Protein NMR Spectroscopy. Principles and Practice (2010) by Cavanagh, Skelton, Fairbrother, Rance and Palmer III (Amazon)
Fundamentals of Protein NMR Spectroscopy (2006) by Rule and Hitchens. (Amazon)
RNA, DNA:
NMR Spectroscopy of RNA (2003) by Fürtig, Richter, Wöhnert, and Schwalbe
Conformational characterization of duplex DNA with solution-state NMR spectroscopy (2022) by Sathyamoorthy, Sannapureddi, Negi and Singh
NMR in Solids:
Nature Reviews Methods Primers: Solid-State NMR Spectroscopy (2021) by Reif, Ashbrook, Emsley and Hong
A nicely visual introduction to NMR principles:
Principles of NMR Spectroscopy: An Illustrated Guide (2016) by Goldenberg
Pocket-sized guides, by Pj Hore:
Nuclear Magnetic Resonance (2015; Oxford Chemistry Primers)
NMR: The Toolkit: How Pulse Sequences Work (2015)
Web resource by Joseph Hornak: Basics of NMR
Others:
Hans Reich’s collection; NMR for Chemists
ANZMAG Lectures on YouTube
Open NMR Wiki
NMRhub (NMRbox, BMRB, NAN & NUScon)