so as i explained earlier there is 10 vowels and 11 double vowels

but here i will explain the sound of the vowels.

vowels; ㅏ ㅑ ㅓ ㅕ ㅗ ㅛ ㅜ ㅠ ㅡㅣ

we can kinda deal the vowels up in two groups. horizontal vowels and vertical vowels.

horizontal vowels: ㅏ ㅑ ㅓ ㅕㅣ. goes on the right

vertical vowels: ㅗ ㅛ ㅜ ㅠ ㅡ. goes on the bottom

ㅏ(a) andㅑ(ya) their difference is that the ㅑ has an extra stroke which ad an Y.
but their A makes the ar sound, so it doesn't make the A sound as there example is in Alice.

ㅓ(eo) and ㅕ(yeo). again their difference is that the ㅕ has an extra stroke which ad a Y. this is also instead of eo written as u or ou, like jungkook, Moonbyul or dahyun. and chaeyoung

ㅗ (o) and ㅛ(yo). and again the extra stroke ad a Y

ㅜ(u/oo) and ㅠ(yu/yoo). and again the thing with the extra stroke

ㅡ (eu) you probably know this from "fakeu love". it's often used to connect consonants

ㅣ(i, but it doesn't make the "ai" sound but the "ee" sound)

but the ㅡ andㅣdosen't have an extra stroke that adds an "y" like example "yi" would be written with just an "i". Byul-yi would be 별이 which is Byul-i.

there is also double vowels.

double vowels: ㅐ ㅒ ㅔ ㅖ ㅘ ㅙ ㅚ ㅝ ㅞ ㅟ ㅢ

we can deal them up in two groups
ㅐ ㅒ ㅔ ㅖ(when it comes to spelling these is used the same way as other vertical vowels)
ㅘ ㅙ ㅚ ㅝ ㅞ ㅟ ㅢ

first we have ㅐ(ae) and ㅔ(e) they sound really similar but the ㅐ is slightly stronger and the mouth would be a little more open. the ae also sometimes get used as an A, because the Hangeul A only makes the ar sound. so they use the ae for example in Alice which is 앨리스 and not 알리스.
ㅐ as you can see is mad up of ㅏ+ㅣ=ㅐ, this isn't quite it for ㅔ(ㅓ+ㅣ=ㅔ)
and if you ad a stroke then we have ㅒ and ㅖ.
but if you have struggle with the difference between ㅐ(ㅒ) and ㅔ(ㅖ) it's okay, some korean people will also get it wrong sometimes.
(quick note; the e makes the sound it makes in Emma, but not as it does Eclipse or in Elon)

then we have the other double vowels, so lets start on them

ㅘ(o-a/wa) is a combination of ㅗ+ㅏ=ㅘ

ㅙ(o-ae/wae) is a combination of ㅗ+ㅐ=ㅙ

ㅚ(oe) is a combination of ㅜ+ㅣ=ㅚ. it made up of o and i but the i is pronounced as an e

ㅝ(u-eo/weo/wo) is a combination of ㅜ+ㅓ=ㅝ

ㅞ(u-e/we) is a combination of ㅜ+ㅔ=ㅞ

ㅟ(u-i/wi) is a combination of ㅜ+ㅣ=ㅟ

ㅢ(eu-i/ui/ee) is a combination of ㅡ+ㅣ=ㅢ

but if you wanna example write "wu/woo" then they just use an "u". like Jiwoo is 지우 which is Ji-u