What is the role of word stress in English language?
Fluent English speakers use word stress to communicate rapidly and accurately, even in difficult conditions. If, for example, you do not hear a word clearly, you can still understand the word because of the position of the stress.
What is the penultimate stress rule?
PENULTIMATE STRESS RULE
If the penultimate (second-to-last) syllable is long, then stress it. If the penultimate syllable is short, then stress the antepenult (third-to-last syllable).