A prefix is a group of letters added to the beginning of a word to change its meaning or create a new word. For example, the prefix "un-" added to the word "happy" changes the meaning to "unhappy." Similarly, the prefix "re-" added to the word "do" changes the meaning to "redo."
A suffix is a group of letters added to the end of a word to change its meaning or create a new word. For example, the suffix "-ful" added to the word "beauty" changes the meaning to "beautiful." Similarly, the suffix "-ness" added to the word "happy" changes the part of speech to a noun, creating the word "happiness."
Therefore, it is not true that neither a prefix nor a suffix will change the meaning or the part of speech of a word.