Equation for Search Resolution

Good afternoon everyone, I have the following question, there is a formula to calculate what is the best resolution in the search for the fourier transform, for the number of measurements we have, the time span, and the spacing (sampling frequency) , I am going to show it as it appears in the conference of Matthew Templeton https://aavso.org/time-series-tutorial

in frequency: dv = 1 / N (delta)
in days:  dP = P ^ 2 / N (delta)

Where N is the total number of samples (592) and (delta) is the space between samples (1 days)

then it is simply said, 1 / (period of time covered by the data in days). but and if I have 20 points that span 80 years, somehow the number of points has to influence.

I wish someone could give me an example with these parameters:

592 measurements
81 years (29565 days)
sampling frequency 1 day

Thanks in advance