How can you create a service like lingq?

Question

Software design

Hello.
The language learning service lingq has a text reader.

When you click on a word in the right block, a translation appears, you can voice the word, examples of use, part of speech, synonyms, etc.
How can this be done?
It is clear with translation, but how can you implement everything else for multiple languages ​​and without using third-party services like google translate api?

Answer 1

1. Lots of frontend for working with words and phrases
   
2. Lots of backend to support the frontend
   

Answer 2

you can pick up the ancient analogue of Learning with Texts (LWT)