Installed, but the button to translation is nowhere to be found. Restarted my Firefox, restarted my laptop. Unfortunately, this ads-on appears to be non existing.
UPDATE: It's 80.0.1 (64 bit). But actually while searching for that information I've found out that I am using anonymous browsing, which was blocking the add-on.
All is well now, I am changing the stars. Also I do appreciate your concern. Thank you.

非常好，终于找到个个人十分满意的翻译器，不用跳转就可以直翻网页，就和在谷歌上使用翻译的感觉一样。

This is what I was missing in Firefox

Perfectly!

This works FANTASTIC on Fennec for Android. Why can't I install it on official, latest Firefox from Mozzila?

Просто идеальное расширение. В нем есть быстрый перевод, и все удобства.

非常不错的网页翻译，不用跳转直接翻译

блестяще

O Melhor e mais rápido tradutor de páginas e NÃO MOSTRA AQUELA BARRA CHATA DO GOOGLE, Perfeito! Eu não queria usar o Firefox só por causa da tradução de sites, agora amooo! Obrigado desenvolvedor, você fez o que ninguém fez.