What do u mean by type of audio?

Question

this is related to audio,html5

Answer 1

They don't tell about "type" of audio in the sololearn course, part html5/audio ^^

I guess you are talking about "file format", which is often called "file type"... and that the course talk about 3 file formats actually supported, may depending of browsers capabilities ( but it's not as nasty as for video format/type :P ).
The "type" of audio in this context is about the codecs used for encoding and the file format used as container for it ( mp3, ogg, wav... are both specific codecs, and containers able to store many different codecs )...

Answer 2

you can add audio file to your html page using <audio> tag...

for example,

<audio controls>
<source src="AudioName.mp3" type="audio/mp3">
</audio>

Answer 3

the file extension of the audio like mp3 or mp4