Meaning of 切磋琢磨合 in Japanese

君の実力なら楽勝だとは思うが、それに驕らず、まずはクラスのみんなと切磋琢磨していって欲しい。
With your ability it should be a doddle, but please don't be prideful of that but first apply yourself dilligently with everyone in your class.

もちろん、実際に「はやぶさ」が太陽に近づいているわけではなく、図のように地球から見て太陽の反対側に位置するだけですが、このような現象を「合」と呼びます。
Of course "Hayabusa" is not actually closing in on the Sun, it is just positioned as in the figure so that, seen from the Earth, it is on the opposite side of the Sun; this is called 'conjunction'.