Historically, the Torah has been chanted to a regularized tune and rhythm. This made memorization of the text (in Hebrew) far easier, and acts as a form of memory aid. It also provides a musical element to the reading and services.
The language of Ancient Hebrew had no written vowels; to a speaker of the time who could concurrently understand the text, there was, however, little ambiguity: the context would make clear the appropriate (unwritten) vowels to insert before, between or after the written consonants so that the words, as a group, formed a sensible sentence. To help later readers of what became a dead language, a system of vowel markings (dots, dashes, and other symbols above and below the consonants) called pointing was established. The Torah itself, however, is always in non-pointed Ancient Hebrew.
Trope relies on a similar set of independent markings above and below the Ancient Hebrew letters, but these are a form of musical notation indicating the stylized pitches and rhythms to be applied to the syllables of the Hebrew word during the chanting. Ancient Hebrew, when marked with both pointing and trope, makes it possible for a modern reader to pronounce and musically chant the words and phrases without needing to rely on any understanding of the ancient language, nor a memory of the musical form (just as Western musical notation accompanied by printed lyrics allows someone to sing a song they have not heard before).