The indefinite article comes BEFORE the noun - un for masculine and neuter, o for feminine - which is the opposite of the definite article, glued onto the end. So un tren but trenul, o cafea but cafeaua.
Examples
- Aș vrea o salată, vă rog.
- I'd like a salad, please.
- Un ceai cu lămâie, vă rog.
- A tea with lemon, please.
- Este o cafenea bună aici.
- There's a good café here.
The mistake to avoid
One article goes in front and the other goes on the end - un tren and trenul, never "un trenul".
Where this fits in
Food & ordering, Romanian A1: Order at a café or restaurant, ask for the bill, and talk about basic food and drink.