Commas are used after introductory words, clauses, or phrases to set them apart from the main sentence.

逗号也可以用在引导词、从句和短语之中，来把它们和主句区分。

There, the clause " which has very good desserts" is not essential; you can understand the main sentence without it: " My favorite restaurant is two blocks from here" .

在那里，“which has very good desserts” 这个子句不是必须的；没有它你也能理解主要句子：“我最喜欢的餐厅离这里有两个街区” 。