Learn Dutch: Stel dat we wat mooie kandelaars vinden tijdens het snuffelen? - Suppose we find some beautiful candlesticks while rummaging?

Yes! While you probably first learned wat for uncountable nouns (like wat water for "some water"), it is also very commonly used with plural countable nouns to mean "some" or "a few". Here, wat mooie kandelaars means "a few beautiful candlesticks". It functions just like the phrase een paar.

Why does mooie get an -e ending here?

When an adjective comes before a plural noun like kandelaars, it always gets the -e ending. It doesn't matter if the singular noun is a de or het word, or what kind of determiner comes before it. Since wat acts as the determiner here for a plural noun, mooi becomes mooie.

Why is the verb vinden placed where it is, rather than right after the subject we?

The phrase stel dat ("suppose that") uses the word dat, which introduces a subordinate clause. In Dutch subordinate clauses, the conjugated verb (vinden) is pushed to the end of the clause. The prepositional phrase tijdens het snuffelen is tacked onto the end as extra information, which is a common and natural exception to the strict "verb at the end" rule.

I learned that snuffelen means "to sniff". How does it mean "rummaging" here?