I for illu

I for illu (i as in pin)

ఇల్లు
ఇ=i
ల్లు=llu
ల+ఉ=లు
la+u=lu
The doubling of consonant l is denoted by the side wise 3 like symbol under the consonant.
Always remember in Telugu, when you add the vowel sign to a double cobsonant then the vowel sign belongs to the cosonant written as vaththu as shown below.

గ్రుడ్లగూబ
Consider the above word, gruDlagooba(owl)
ga+ru=gru
గ+రు=గ్రు
Although the vowel sign is written for ga(గ) it actually belongs to ర rather than గ.
Similarly,
డ్+ల=డ్ల

Although it looks complicated it is a simple rule, if two consonants come one after other without a consonant in between the second consonant is written as a vaththu below the first consonant and the second consonant's vowel sign is written to the the first consonant.