Adverbs of location indicate the position, where an event happened that is described by the verb.

Example: I do it here.

It seems trivial, but there are two different groups of local adverbs. The one describes a place, where an action takes place. The other describes a movement towards a certain point.

Example: I do it there.
Example: I go there.

In English there is no difference and therefore it might seem a bit simple. But in German there is a real difference, therefore we were talking about these two groups.

Examples   Er ist dort. He is there.   Er geht dorthin. He goes there.   Er ist hier. He is here.   Er kommt nicht bis hierher. He does not come here.   Er ist da. He is there.   Er kommt nicht bis dahin. He cannot reach there.

It is clearly to be seen that dort turns into dorthin, da into dahin and hier into hierher, if a verb of movement is used.

One cannot just transfer the English logic into German:   incorrect: Er geht dort.     incorrect: Er kommt bis hier.     incorrect: Er kommt nicht bis da.

If you might ask, why on earth you can't do so, since in English it is possible and people still understand the difference, we only can give a simple and not very convincing answer. No idea, it's just the way it is.

These adverbs have to be remembered as they are   dort, da there   dorthin, dahin (to) there   hier here   bis hierher (to) here   bis dahin, bis dorthin (until) there