Your five year old should have speech that is very similar to an adult.  He should be able to say most sounds, most of the time.  Errors will still occur but they should be diminishing.  You should understand your child, as should everyone they meet. 

If your child has trouble with the /s, r, or th/ sounds, do not worry.  These are late developing sounds.  Some children don’t develop these until later, around 7.