How does this notch filter work?
Without any calculation:

The combination C2-R4 forms a highpass in the feedback loop (and, thus, acts as a lowpass for the input signal)

The combination C1-R3 forms a simple highpass in the forward path.

Both functions - related to the NON-INVERTING input - make together a (positive) bandpass response.

At the same time, the input signal is connected also to the inverting terminal. Hence, at the output we have the DIFFERENCE between the (positive) bandpass signal and the constant (negative) amplified version of the input signal (the corresponding gain: -R2/R1).

If the negative gain has a value which can compensate the bandpass maximum value (at cener frequency), the output is zero at this single frequency.