Translation:To give money
This phrase is a zombie - it has an unnecessary mutation at the start.
rhoi arian means 'to give money' or 'giving money', rather than 'give money'.
Yes, arian also means silver, so this sentence in the correct form could mean 'give silver'.
Other sentences with this meaning could be:-
Mi wnes i roi arian i Owen = I gave money/silver to Owen.
Dw i wedi rhoi arian i Owen = I have given money/silver to Owen.
The context would be important.
Interestingly the North Wales word for money is 'pres' which also means 'brass'.
Northern England also has the word 'brass' as a commonly used slang for money.