accents

Greek has three different accent marks (BBG 4.2.3):

ά  –  acute

ᾶ  –  circumflex (often a sign that a contraction happened)

ὰ  –  grave

Hebrew:

Most words are accented on the last syllable.  If this is not the case, then an accent is used to mark the accented syllable.  See here or watch this.