I often hear these mistakes made by German speakers who are learning English.
They say: I explained her the problem.
Remember, in English we explain something to someone. Therefore the ‘to’ is missing in this sentence.
There is also a problem with the word order.
Correction: I explained the problem to her.
Further examples:
He explained the situation to me.
They explained the rules of the game to him.
We explained the reasons for our decision to them.
Have fun learning English!
Louise