A prefix is a group of letters which you can add to the beginning of a root word to change the meaning of the word.
e.g. mis + fortune = misfortune
A suffix is a word ending. It is a group of letters you can add to the end of a root word. e.g. walking, helpful
A root word stands on its own as a word but you can make new words from it by adding beginnings (prefixes) and endings (suffixes).
Here are some games for you to practise. Good luck and enjoy them!