I wanted to say the sentence "I have a replacement class this Saturday". I translated "replacement class" in Google translate and got 替换课程. But when I typed the full sentence on Google translate it is 替补课. So should my sentence be 这个星期六我有替换课程 or 这个星期六我有替补课 or is there any other more approriate/colloquial way to say it?
The scenario you described is usually called 调（tiáo）课 in Chinese. I am not sure if there is a corresponding noun for replacement class in Chinese, but the sentence you had
I have a replacement class this Saturday
can be translated to
in addition to what @zyy answered:
调 means making adjustments 课 means class
调课 sometimes implicitly means that we are swapping two classes, so it is slightly different from
other possible translations: