The words sloe, slow sound the same but have different meanings and spellings. Why do sloe, slow sound the same even though they are completely different words?
The answer is simple: sloe, slow are homophones of the English language.
See blackthorn.
Either of two eastern North American plum trees or shrubs, Prunus alleghaniensis, having dark purple fruit, or P. americana, having yellow or red fruit.
The tart plumlike fruit of either of these plants.
Lacking in promptness or willingness; not precipitate: They were slow to accept our invitation.
Not moving or able to move quickly; proceeding at a low speed: a slow train; slow walkers.
Marked by a retarded tempo: a slow waltz.
Taking or requiring a long time: the slow job of making bread.
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.
If they are spelled the same then they are also homographs (and homonyms); if they are spelled differently then they are also heterographs (literally "different writing").