how do I make the talk command say stuff instead of just saying H-e-l-l-o to ''hello!''?

TALK can only speak Japanese, because Japanese is a very easy language to interpret and pronounce. English speech synthesis is very complex so all it does is say the letters.

Like Alex says, Japanese has too few phonemes to pronounce English-based words. If SmileBASIC tries to pronounce "hello", it'll pronounce like "harrou" because Japanese cannot separate the pronunciation of "L" from "R".