This is the hallmark of Tamil. While Sinhala speakers often use ළ (retroflex L) to approximate it, the true Tamil "Zha" is produced by curling the tongue back further without touching the roof of the mouth.
Tamil also uses "Grantha" letters to represent sounds borrowed from Sanskrit, which have direct equivalents in the Sinhala alphabet: (ja) → ජ ஷ (ṣa) → ෂ ஸ (sa) → ස ஹ (ha) → හ க்ஷ (kṣa) → ක්ෂ Sinhala Alphabet Guide: Learn Vowels, Consonants and Script full tamil alphabet with sinhala letters
Tamil has 12 vowels. Unlike Sinhala, which has separate characters for "æ" sounds, Tamil vowels are straightforward. Tamil Letter Sinhala Equivalent Pronunciation (IPA) අ a (as in 'cup') ஆ ආ ā (as in 'far') இ ඉ i (as in 'it') ஈ ඊ ī (as in 'eat') உ උ u (as in 'put') ஊ ඌ ū (as in 'boot') எ එ e (short 'e') ஏ ඒ ē (long 'e') ஐ අයි ai (as in 'eye') ஒ ඔ o (short 'o') ஓ ඕ ō (long 'o') ஔ අව් au (as in 'out') This is the hallmark of Tamil