The words he'll, heal, heel sound the same but have different meanings and spellings. Why do he'll, heal, heel sound the same even though they are completely different words?
The answer is simple: he'll, heal, heel are homophones of the English language.
Contraction of he will.
To restore to health or soundness; cure. See Synonyms at cure.
To set right; repair: healed the rift between us.
To restore (a person) to spiritual wholeness.
To become whole and sound; return to health.
The rounded posterior portion of the human foot under and behind the ankle.
The corresponding part of the hind foot of other vertebrates.
A similar anatomical part, such as the fleshy rounded base of the human palm or the hind toe of a bird.
The part, as of a sock, shoe, or stocking, that covers the rounded posterior portion of the human foot.
Definitions from The American Heritage® Dictionary of the English Language, 4th Edition and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.