"网球课"的英文翻译是"tennis lesson"。这个词组表示一次教授网球技术的课程或者训练。例如，你可以这样说：

I'm going to a tennis lesson this afternoon.
My coach is giving me a tennis lesson on Saturday.

如果你想表示这是一节关于网球的课程，你可以这样说：

I'm taking a tennis class at the community center.
My school is offering a tennis course this semester.

希望这些翻译能帮助你！