Then he smiled and told me I would receive an extra thousand

Then he smiled and told me I would receive an extra thousand pounds a year!出自新概念中,请问（1）a year 表示就是今年一年,还是每年呢,那么每年不是应该用every year吗,（2）另外句子中已经有具体的数字 thousand 了,为什么前面加an呢