In addition to the vav, yud, aleph, and (rarely) ayin, which are mentioned above a partial vowels, there is also the heh which has an “H” sound at a consonant, but very often appears at the end of a word to signify a “-ah” sound, or at the beginning of a word for a “ha-” sound.
Hebrew’s lack of true vowels is often demonstrated by spelling “AMERICA” as “MRC”, but this is a fallacy. “America” is spelled in modern Hebrew with six letters: aleph, mem, resh, yud, kuf, heh, which can be tranliterated as either “AMRYKA” or “AMRICA”. Yes, the missing “E” must be supplied by familiarity with the word, but still, the alleged lack of vowels is an exaggeration.