Stressed syllables may sound longer and/or louder than unstressed syllables. The word 'attract' is stressed on the second syllable: əˈtrękt. Putting the symbol (') before a syllable marks it as stressed. Notice also that the vowel of an unstressed syllable can often be reduced: in our example, 'a' of attract is pronounced as schwa [ə].
Learn more about syllable stress: see page 93 here