The maqaf or (older) maqqeph is a punctuation mark in Hebrew roughly equivalent to a hyphen. It's a horizontal stroke ־ at the top of the line, rather than in the middle. It means "binding", and the main effect is to bind the two words it joins together phonetically into a single accented word.

This typically changes the vowel in the first word from long to short. For example, the accusative particle is the word êt, but in combination with another word it becomes short et-.

Several words, including ze 'this', also cause the following consonant to be doubled, taking the dagesh dot inside it.

The Unicode for maqaf is ־

R.K. Harrison, Teach Yourself Hebrew, English Universities Press, 1955