The German ö is like the vowel in English "her" or "bird" (without pronouncing the "r"). Say "eh" but round your lips into an "o" shape — that's the ö sound.
How to make this sound
Try this: say "eh" (like in "bed"), then round your lips like you're saying "o" — but keep making the "eh" sound. That mix of "eh" + rounded lips = ö. You'll see ö in many plurals where the base word has "o".
Hear something close to ö
English
her
the vowel here is close (drop the "r")
English
bird
same vowel — imagine it without the "r"
How to
say "eh" + round lips
= the ö sound
Hear the difference: o → ö
Read both words aloud — listen how the open "o" shifts to the rounded "ö" when the umlaut appears.