How to use API of BTC.com
BTC.com APIs are Web APIs. This means you can use them by making HTTP requests (GET/POST requests).

Like all online APIs, you can access them through whatever program/script you want, provided they are able to make HTTP requests and handle the answers.
Requests/responses are usually encoded using the JSON format.

You can find a good introduction here.

You can choose your favorite language. However, since data is in JSON format, I would suggest to use either Javascript or Python.
In Python you can use the 'request' package. Here you can find a quick introduction.

In Javascript you have the 'request' library.
I wrote a generic lib to make Web API requests: https://github.com/frz-dev/webapi.js/blob/master/webapi.js