The word 'er'
You will hear it in every conversation. You do not need to master it — you need to recognise it.
er is the hardest little word in Dutch. It does four unrelated jobs, and it is everywhere.
Good news first: you can speak decent Dutch while getting er wrong. It almost never blocks understanding. So relax.
Here are the four jobs, so you can recognise them when you hear them.
Er is een probleem.
There is a problem.
1. Same as English 'there is'.
Ik ben er geweest.
I have been there.
2. Means 'there', a place.
Ik heb er drie.
I have three of them.
3. Means 'of them', with a number.
Ik denk er niet aan.
I'm not thinking about it.
4. Stands in for 'it'.
Job 4 is the one that feels alien. Dutch does not like saying 'about it' or 'with it'. Instead it glues er onto the front of the small word.
Ik ben ermee bezig.
I'm working on it.
met + het becomes ermee
Wat vind je ervan?
What do you think of it?
van + het becomes ervan
Ik kom er later op terug.
I'll come back to it later.
op + het becomes er … op
Do not study er. Collect four or five whole phrases with er inside them, use those, and the pattern will sink in by itself.