自学印地语介绍

कै kai Similar to the vowel in 'cap', but flatter
को ko A pure '0', less rounded than in 'cold'.
कौ kau  Similar to the vowel in 'hot'.
And here's some more reading and writing practice:

कान kan car
कृपाkrpa kindness
खड़ा (khada) khara standing
चाय(chaay) cay tea
तोता tota parrot
दुकान dukan shop
दूरduur  far

पानी pani water
भारत bharar India
माकन makan house
वाराणसी varnasi ( varanaasi)Vaenasi
सितार sitar sitar
सौ  sau hundred
है hai is

At this point you should practise writing out these vowel signs attached to all the consonants until they become really familiar.
These vowel signs can only be used when they have a consonant sign to cling to. In other positions, such as at the beginning of a word, the vowel is written with a vowel character. The first in the list is the 'inherent' vowel:

अ a
आ aa
इ i
ई ii
अब ab mow
आज aaj today
इधर idhar over here
ईरान (iiran) iran Iran

उ u  उधर udhar over ther
ऊ uu ऊपर upar up
ऋ ri  ऋण (rinn) r.n. debt
ए e  एक ek one
ऐ ai ऐसा aisa such
ओ o  ओर or direction
औ au और aur and

And here are three words in which vowel characters appear as the second of two  equential vowels (i.e. neither at the beginning of a word nor after a consonant):

कई kai 'several' -ई i follows the syllable "क ka;
उबाऊ  ubau 'boring' - ऊ  uu follows the syllable बाba;
बनाओ banao 'make' - ओ  o follows the syllable ना naa.

Conjunct characters

When two consonant sounds come together without an intervening vowel, we have to cancel or 'kill off' the inherent vowel of the first consonant. For example, in the word 'Hindi' there is no 'a' betw the 'n' and the 'd', so a shortened form of the first consonant, न , is physically joined to the second consonant, द, giving हिन्दी  hindii.

क+य =क्य  क्या kya what?
च+च =च्च बच्चा bacca child
च+छ=च्छ अच्छा accha good
ल+ल=लल बिल्ली billi cat
स+त=सत  हिन्दस्तानी hindustiini Indian