The correct indefinite article for the noun veste is **une**.
Indefinite articles are used before singular countable nouns that are not specific. In French, there are two indefinite articles: un (masculine) and une (feminine).
Since veste is a feminine noun, the indefinite article is une.
Here are some examples:
* Je cherche une veste.
* Elle porte une veste rouge.
* J'ai acheté une veste en cuir.
I hope this helps!