Hamzatu l-wasl, when case :if the final letter of the previous word has no vowel

In book A New Arabic grammar of the written language, In case of Hamzatu l-wasl, when case :if the final letter of the previous word has no vowel, say "it is given a vowel" What does it mean "it is given a vowel"? For Example: In quran 23:14, for instant, at 23:14.6 "ٱلْعَلَقَةَ" have Hamzatu l-wasl, at beginning, and previse word is "فَخَلَقْنَا", so how to pronounced "ٱلْعَلَقَةَ" as previse word's late letter(alif) does not have vowel. Here is