NMR Question

Hi,
I'm looking at a sheet with NMR data for copper.
For "Isotope 1" there is an entry of "26.515441" with the
annotation of "Frequency relative to H = 100(MHz)".
Am I correct in assuming the Cu and basically everything has a
NMR frequency?
In the case of Cu what is the actual frequency?
What I don't understand is what does the
Frequency Relative to H = 100 (MHz) impact the value given of 26.515441???
My guess is that the resonant frequency is somewhat dependent on
the magnetic field as the Cs vapor is affected in the Cs cell of a
Cs vapor magnetometer.
I'm not a physisist so hope for a simple explanation I can understand.
Any help appreciated,
Don