Originally, the Hebrew language had no vowels. Vowels were simply understood by the reader like our blvd. and rd. After the Christian era and the Diaspora, Hebrew became a dead language and traditional pronunciation and understanding were becoming lost. Jewish scribes tried to permanently establish vowel sounds. First, mothers of reading (matres lectionis) were added before the Christian era to indicate long vowels, and they are seen in the Dead Sea Scrolls. Around the 5th century A.D., the Masoretes added vowel signs to indicate short vowels in at least 3 different systems of signs over space and time. The one used today is from Masoretic scribes in Tiberias. Vowels and half-vowels are indicated by dots or dashes above or below the consonants.
(The Origin of the Bible: Newly Updated by F. F. Bruce, J. I. Packer, Philip W. Comfort, and Carl F. H. Henry, 2020. Biblical Languages by Larry Walker. Page 221-222)