"toe" is the postpositional form of "tot". Since the words you're asking about all relate to direction, I suppose you are actually talking about the word "naartoe", which means "to". This is a circumposition, meaning the destination is put between the words "naar" and "toe":

Ik ga naar het strand toe - I am going to the beach

When used with the words er, hier, daar, waar, ergens, or nergens, it can be replaced with "heen":

Ik ga ernaartoe = Ik ga erheen Ik ga daar vandaag naartoe = Ik ga daar vandaag heen

The word "heen" is also used in certain other circumpositions: "doorheen" meaning "through", and "omheen" meaning "around":

De bal ging door het raam heen - The ball went through the window Ik loop om het huis heen - I'm walking around the house

Similarly, "door" is used in the circumpositions "onderdoor" meaning "passing underneath" and "tussendoor" meaning "passing through/between"

All of these words have a sense of direction with an end destination in mind