Y
⟨yh⟩ was used in the pre-1985 orthography of Guinea, for the "ejective y" or palatalized glottal stop (/ʔʲ/) in Pular (a Fula language). In the current orthography it is now written ƴ. In Xhosa it is used for the sound / j̈ /. In a handful of Australian languages, it represents a "dental semivowel".
⟨yi⟩ is used in Mandarin pinyin and Romanized Korean to write the vowel /i/ in initial position.
⟨yk⟩ is used in Yanyuwa for a pre-velar stop, /ɡ̟ ~ k̟/.
⟨ym⟩ is used in French to write the vowel sound /ɛ̃/ (/im/ before another vowel), as in thym /tɛ̃/ "thyme".
⟨yn⟩ is used in French to write the vowel sound /ɛ̃/ in some words of Greek origin, such as syncope /sɛ̃kɔp/ "syncope".
⟨yr⟩ is used in Pinyin to write the trilled vowel /r̝/ in languages such as Yi.
⟨yu⟩ is used in romanized Chinese to write the vowel /y/. In Mandarin pinyin it is used for /y/ in initial position, whereas in Cantonese Jyutping it is used for /y/ in non-initial position. (See jyu.)
⟨yw⟩ is used for /jʷ/ in Arrernte and for doubly articulated /ɥ/ in Yélî Dnye.
⟨yx⟩ in used in Nambikwara for a glottalized /ˀj/.
⟨yy⟩ is used in some languages such as Finnish to write the long vowel /yː/. In Haida (Bringhurst orthography) it's glottalized /ˀj/.
Read more about this topic: List Of Digraphs In Latin Alphabets