U+1EF3 Latin Small Letter Y with Grave

The Wikipedia has the following information about this codepoint:

The grave accent (◌̀) ( or ) is a diacritical mark used to varying degrees in French, Dutch, Portuguese, Italian and many other western European languages as well as for a few unusual uses in English. It is also used in other languages using the Latin alphabet, such as Mohawk and Yoruba, and with non-Latin writing systems such as the Greek and Cyrillic alphabets and the Bopomofo or Zhuyin Fuhao semi-syllabary. It has no single meaning, but can indicate pitch, stress, or other features.

For the most commonly encountered uses of the accent in the Latin and Greek alphabets, precomposed characters are available. For less-used and compound diacritics, a combining character facility is available. A free-standing version of the symbol (`), commonly called a backtick, also exists and has acquired other uses.