a full range speaker is often a 51/4 that should play most all freqs. but is often a cheap speaker or a speaker that play as much of the music spectrum as possible.
the human range of hearing is from 20hz. to 20khz, or 20,000 hz.
20 hz. is low bass and everything under 20 hz. is inaudible you cannot hear it but u can feel it, you know the car next to u playing bass that shakes your car.
20khz. is the highest u can hear anything above is like a dog whistle ur dog can hear but ur dog can.
a full range often plays from 80hz. to around 10k. so it plays most of the music spectrum but to get the whole music spectrum u need a Subwoofer and a tweeter.
a sub plays from 20 hz. to like 100 hz. and a tweeter plays from around 4khz. to 20khz.
the idea is to have a mid range that will play from 100hz. up to 4000k. then the tweeter takes over and play 4000 to 20k.hz.
the sub plays from 20 hz. up to 100hz.
there is no or few full range speakers a 1 inch tweeter cannot play bass, and a 12 inch Subwoofer cannot play high frequencies.
so u have a sub, a pair of mids, and a pair of tweeters, to play full range, a full range speaker basically does not exist cause it is impossible to play real low bass cause the speaker is too small, and cannot play high freqs cause it is too big.
sub, mid -n- tweeter to get the whole music spectrum.
start googling and researching, there is much to be learned.