We also use er, hier, and daar to replace the pronouns het, dit, deze, die, and dat. We do this when these pronouns precede a preposition.
For example: in het (in it) becomes erin, over dit (about this) becomes hierover, and voor dat (before that) becomes daarvoor. These are just a few examples. There are many more possible combinations.
You can read more about this phenomenon on the page about the Dutch pronominal adverbs.
When we use er, hier or daar this way, the main clause always contains a 'postposition' at the beginning of the right side. The postposition is the preposition that would have preceded het, dit or dat (had it been allowed to).
|It does not make any sense to me.
The literal translation of this expression is: "I cannot tie a rope to it".
|They have benefited from it.
The literal translation of this expression is "They have done their benefit with it".
|You still easily fit in it.