Although Tom's only an amateur he's a first-class player.是什么意思？

Although Tom's only an amateur he's a first-class player.

虽然汤姆只是个业余爱好者, 但却是一流的高手。

although

conj. 尽管，虽然，但是，然

例句
He was in love with her, although he did not put that name to it.
他爱着她，虽然他没有将其称为爱。

only

adj. 唯一的，仅有的，最好的，最适当的；adv. 只，仅仅，结果却，不料；conj. 但是，可是，要不是；

例句
Outsiders who wed islanders are given only three years' right of abode at first.
岛外的人和岛民结婚之初只能获得三年的居住权。

an

art. 一（在元音字母前代替不定代词a），一任一某一，一个；

例句
He started eating an apple...
他开始吃苹果。

amateur

n. 业余爱好者，外行，生手；adj. 业余的，非职业的，外行的；

例句
Jerry is an amateur who dances because he feels like it...
杰里是个业余跳舞爱好者，他跳舞是因为自己喜欢。

player

n. 演员，[体]运动员，[音]演奏者，播放机；

例句
There is no comparison between the knowledge and skill of such a player and the ordinary casual participant.
临时的普通参赛者无法与这种选手所掌握的知识和技巧相提并论。