Today’s lesson in how weird English is:
Words which are spelled the same but act as different parts of speech are typically pronounced with emphasis on different syllables. For example, “contract” is a noun and a verb. The former is pronounced CON-tract, while the latter is con-TRACT. A driver’s PER-mit will per-MIT you to operate a car. When you add-RESS an envelope, you usually write your ADD-ress in the corner. You might ob-JECT to an obscene OB-ject. A police officer probably sus-PECTs a SUS-pect. And so on. Note that nouns emphasize the first syllable, and verbs the second.
Also, words which are given different endings tend to change which syllable is emphasized. Take “photograph” for example; it’s pronounced with the emphasis on the first syllable: PHO-to-graph. But add a “-y” and it becomes pho-TO-graph-y. Add an “-ic” and it’s pho-to-GRAPH-ic. Consider Einstein’s theory of rel-a-TI-vi-ty, which explains rel-a-ti-VIS-tic phenomenon between the REL-a-tive positions of things.
Oh, and of course there are plenty of exceptions to these not-quite-rules. Like many idiosyncrasies of English, this is one of those things you just have to know because you’re a native speaker; if you’re learning the language you may never get all the emphases right. Whee.