Is it possible to have my app communicate with moodle?

I am thinking about building a student app, that would use Moodle data, and notify the user when a new file has been uploaded, and perhaps do something like checking your grades etc. I'm quite new to android programming and can get easily confused with the technical terms. I've looked around the web and found that there is an API, but I dont really 100% know what that means. Which is weird since I've communicated with API's like the OpenWeatherMap one and uTorrent. Would Moodle's api do the same? Make it easier for me to get their data? Their descriptions are really technical and I can not understand much.