In order to give a wider frequency response, the loudspeakers incorporate several types of loudspeakers in the loudspeaker box and each one takes care of "filling" a certain frequency, in which case each single loudspeaker is called "via".
For example, a 2-way speaker normally incorporates a tweeter and a woofer. While a 3-way cabinet commonly incorporates a tweeter, a midrange and a woofer. There are, for example, 3-way speakers that can incorporate more tweeters, more midrange and more woofers, but still remain 3-way speakers, because this is the number of frequency bands covered.
Normally 3-way speakers are the ones that best cover the entire audible frequency spectrum, giving better sound quality.