Abar over a vowel indicates that the vowel is
long
short
unaccented

Long.

Explanation:

Long vowel sounds usually contain a bar over them. The Long vowels are marked with "macron"(ancient Greek terminology) and are referred to as the sounds whose pronunciation is similar to the vowel name. The vowel length and representation is a crucial phonemic factor as it defines the distinction among the dialects. Thus, the bar over the vowel sounds is significant as it allows the readers to distinguish between the long and short vowel sounds, to decipher IPA. It also helps to know the authorial message reflected through the vowel sound and tone that is reflected by the bar.