Drop your jaw moderately. Touch the tongue tip behind the bottom front teeth and lift the mid-front part slightly toward the roof.

Americans pronounce eh as eh (/ɛ/). It's 1 sound in 1 syllable. One vowel, one syllable — short and clean. What you see is what you say.
Record yourself saying "eh" and play it back. The mic stays on your device — nothing's uploaded.
1 syllable, 1 sound. Explore each sound's mouth shape and how it's made.