English tutor Alice here to help you with pronouncing ‘Man’ and ‘Men’
Start with a Mmm sound for ‘Man’ then open your mouth wide vertically by dropping your jaw for the A sound. Like your making the letter A sound. Then make a short N sound.
For ‘Men’ start with the Mmm sound. Then with your lips apart horizontally and teeth close together but not closed completely make the eh sound like the E in ‘egg’ and then say nnn sound.