The folks who run the miniDSP organization give a nice overview of how a PARAMETRIC eq differs from a traditional "graphic equalizer" -- https://www.minidsp.com/applications/dsp-basics/peq-vs-graphic-eq

Key points --
In a parametric equalizer, each filter cuts or boosts a range of frequencies. Each filter has three controls:

frequency: the center of the frequency range to be cut or boosted
gain: the amount of boost or cut
Q: the "sharpness" of the boost or cut, with higher Q meaning a narrower filter

Parametric EQ thus allows a single filter to be very narrow or quite wide, and it is therefore very useful for correcting frequency response errors in a loudspeaker or reducing peaks caused by room modes. When implemented digitally, parametric filters can also take the shape of a "shelving" filter, which boost or cuts frequencies above or below the filter frequency.

Here is a very nice overview of how one can easily use the free Room Eq Wizard software to measure in-situ speaker response and have the software calculate suggested settings to achieve a desired target curve -- https://mehlau.net/audio/room-correction-peq/