A prefix is a stem that can be applied to the beginning of words to add a certain meaning, whereas a suffix is applied to the ends of words to add a certain meaning.
For example, a prefix could be un. When you add un to the beginning of a word, it reverses the meaning of said word (such as in unable or unhappy).
A suffix could be -ness. Adding this to the end of a word makes it a noun. For example, foolishness and happiness are words with this suffix.
Hope this helps!
