Breakdown of Watjes hebben we er nog vijftig.
hebben
to have
vijftig
fifty
we
we (unstressed form of wij)
nog
still, yet / more, another (with a quantity)
Questions & Answers about Watjes hebben we er nog vijftig.
Why is watjes placed at the very beginning of the sentence?
This is an example of split topicalization. You can move the noun (watjes) to the front of the sentence to emphasize it as the topic, while leaving its quantity (vijftig) near the end. It gives the feeling of 'As for cotton pads, we still have fifty.'
Why is the word er necessary here?
This is the quantitative er. Because the noun (watjes) has been separated from its number (vijftig), Dutch requires er to act as a placeholder. It works exactly like saying 'of them' in English.
Can I leave er out and just say 'Watjes hebben we nog vijftig'?
No, that is grammatically incorrect in Dutch. Whenever a number or quantifier stands alone in the middle field because its noun was moved or omitted, you absolutely must include er.
How would this sentence look if I didn't split the noun and the number?
Besides 'cotton pads', is there another meaning for watjes?