YOU SAID:

My colleague, who sits next to me, is very cool and smart.

INTO JAPANESE

私の隣に座っている私の同僚は、とてもクールでスマートです。

BACK INTO ENGLISH

My colleague sitting next to me is very cool and smart.

INTO JAPANESE

私の隣に座っている私の同僚はとてもクールで頭がいいです。

BACK INTO ENGLISH

My colleague sitting next to me is very cool and smart.