Reference works write pronunciations between slashes, and this word appears as /ədˈvæntɪdʒ/, with primary stress on the second syllable: ad-VAN-tidge. British English often uses a longer vowel there, /ədˈvɑːntɪdʒ/.
It's to your advantage. Glide through the first syllable, land on van, then finish quickly.
Mouth positions to check
Keep the first syllable small: lips relaxed and jaw barely open for the quick /ə/ sound, then touch the tongue ridge lightly for /d/.
Make /ˈvæn/ the loud syllable. Press your top teeth onto your bottom lip for /v/, then open the jaw. British English often uses the longer /ɑː/ vowel here, while American English keeps the /æ/ vowel heard in cat.
Finish with /tɪdʒ/: tap the tongue ridge for /t/, then glide into the /dʒ/ sound, the same final sound as bridge or edge. Let it end quickly.
Saying it in a phrase
It's to your advantage. Stress the middle: ad-VAN-tidge, and let the first and last parts stay small.
The new rule works to our advantage. Push the loudest beat onto van, then shorten tidge so the word ends quickly and cleanly.
Compare with advance: both begin with the same weak ad and carry stress on the second syllable. Saying an advance then an advantage keeps that shared rhythm steady.
Contrast with AD-vocate in an advocate, where stress sits on the first syllable. Saying an advocate beside an advantage highlights which syllable carries the beat in each word.