Hebrew vowels. In Hebrew, words are written solely with consonants. Vowels are either left out, to be mentally filled in by the reader, or written as dots and lines around the letter they are to apply to. If this were so in English, we would write the word "He" with just an H, placing a dot below it for the "ee" sound. To demonstrate, I'll use ה, which is the Hebrew equivalent of H, hey:
ִה

This system occasionally produces words that may be read multiple ways (using the previous example, ה written alone could be read "he", "hi", or "ha", and context would be your only clue). A fair amount of commentary on the Torah is based on this phenomenon.

Anyways, the vowels:

ָה would be read as "Ha"

ַה would also be read as "Ha" (just to confuse people) (So ha!)

ֶה would be read as "Heh"

ִה would be read as "Hee"

ֻה would be read as "Hoo"

ּ הו (yes, this vowel is a character unto itself. Note that as Hebrew goes from right to left, it comes after the letter) is also read as "Hoo", but wait! There's more!

ׂהו is read as "Ho", as in "Land ho!".

For these last two, the dot is almost always omitted, leaving the poor, hapless reader to guess what is meant. What's more, "Ho" is sometimes written with stick and dot, just stick, just dot, OR none, making reading Hebrew a veritable bonanza of fun the whole family can enjoy!