There’s no such thing as “a training”. You either receive training – a general, uncountable noun – or take a training course. You can’t “follow a training” or “give a training”.
It’s one of those cases where the Dutch usage of an English word is in fact different to the native usage. Use:
- the uncountable noun with no article for education and instructions in general, e.g. “all staff receive training in first aid“. This could mean anything from one lesson on the day they join through to refresher courses every year
- a training course or just a course for a number of related lessons, e.g. leading to a qualification
- a workshop, a training session, a lesson or some other such synonym for a single element in the course
Not quite sure how to classify this one: fake English because it’s an English word used wrongly? A valse vriend because the meaning of the Dutch isn’t the same? A grammatical issue of plurals and uncountable nouns? I’d better put it in all of them, I suppose, so that searching the categories will always work.
Prevalence: moderate. A common one on corporate websites and in CVs in particular.
Frequency: high. The confusion is widespread when the word turns up.
Native: no. Although I have seen it – perhaps changing under the influence of so many non-natives using it that way!