In Modern Israeli Hebrew, א(“alef”) represents either a glottal stop (/ʔ/), or has no pronunciation besides that of the vowel attached to it. The pronunciation varies from group to group.
א(“alef”)—along with the other guttural letters, ע(ʿ, “ayin”), ר(r, “resh”), ה(h, “he”), and ח(ḥ, “ḥêṯ”)—cannot receive a dagesh (the dot in בּ(b, “bet”), which can appear in most other Hebrew letters), although there are rare examples where the Masoretes added a dagesh to it.
א(“alef”) is sometimes used to denote a vowel (usually /a/) in words of Aramaic and Arabic origin, in foreign names, and in some other borrowed words.