Open Safari, click on the Browser extension in the menu
Then find translate this plugin in the open page
If you can't find it, you can click the translation option in categories.
And then you can see the translate plugin.
This can be installed directly by clicking Install, but I failed to install
I opened this plugin, the details page appears, click Download Direct Download Plugin
After the download is complete, open safari preferences, select the Extensions tab, drag the downloaded plugin, and a button will appear above safari to translate the page by clicking the button.
Click here to open setting can set the plugin, can choose Google Translate or Microsoft translation, automatic translation or manual translation
I chose Microsoft, manual translation, very convenient, translation effect is also good
Mac Tips--How to install a translation plugin for Safari