What words are spelled the same but have different meanings and pronunciations?

While these words are sometimes called "homonyms" (same words), they are more accurately called homographs (same writing). The term homonym is more frequently applied to words that are spelled differently but sound the same (homophones). Homographs are often impossible to identify without context clues.

Homographs often appear as noun/verb pairs such as

tear (crying) and tear (to rip)

mean (cruel), mean (an average), and mean (defines)

There is a large list of homograph examples at the related link.