If you have good grammar but native speakers still ask you to repeat yourself, stress is your bottleneck. This PDF turns ambiguous speech into crisp, professional English.
A syllable is a single, unbroken sound unit within a word. It consists of a (usually a vowel sound) and may include an onset and coda (consonants).
When in doubt, stress the first syllable of nouns and the last syllable of verbs. You’ll be right 80% of the time.