"Are you putting the jacket on?"
Translation:A bheil thu a' cur na seacaide ort?
Ah, no, na seachaide isn't plural, it's in the singular genitive case.
Direct objects of verbal nouns (except for indefinite singular) take the genitive case. This probably isn't explained anywhere yet.
- seachaid = a jacket
- an seachaid = the jacket
- dath na seachaide = the colour of the jacket
We use the genitive after verbal nouns because in a literal sense what is being said is something like "the putting (on) of the jacket".
Just wait until you get to the plural genitive.