Take 3 words: photograph, photographer and photographic, for example. Do they sound the same when spoken? No! They sound different, because *one* syllable in each word is "stressed" (stronger than the others).
This happens in ALL words with 2 or more syllables:
The syllables that are not stressed are 'weak' or 'small' or 'quiet'. Native speakers of English listen for the stressed syllables, not the weak syllables. If you use Word Stress in your speech, you will instantly and automatically improve your pronunciation and your comprehension.
If you have an English teacher, ask her to help you understand Word Stress. Try to hear the stress in words each time you listen to English - on the radio, or in films for example. Your first step is to hear and recognise it. After that, you can use it!