In some cases you can replace a pun with another pun that works in the target language.
In other cases, where you’re translating a religious text, doing something for scholarly reasons, or you otherwise think your audience would really like to know what’s going on in a text you have to add a translation note.
That’s why translation can be so hard, especially for poems, songs, comedy etc. Double meanings, metaphors, rhymes etc are often lost when translated.
I only understand train station.
In some cases you can replace a pun with another pun that works in the target language.
In other cases, where you’re translating a religious text, doing something for scholarly reasons, or you otherwise think your audience would really like to know what’s going on in a text you have to add a translation note.