This coin weighs only 0.6 gram, and was minted in the reign of D. Manuel I (1495-1521), around the same time that Brazil was discovered by the Portuguese. The denomination is Meio Vintém (Half Vintém), with "vintém" meaning "small twenty", so it's a 10 Réis coin.
What’s interesting in this coin is that its legend is a variation from a catalogued legend:
The reference that is closer to this coin is Alberto Gomes 18.01, +I:EM… in the reverse.
This coin was found in the city of Benfica do Ribaltejo, near the Tejo river. A very interesting coin, indeed.