To most of my research so far, it is the visual of speech sounds. When you look through a dictionary, you'll usually see these things under the main word you're looking for.
For example, you take a word like "Seahorse". You have the word type, and below the word type, you see some fancy looking text.
I will bold this mini dictionary bit for you to show you what we're focusing on.
Seahorse
Noun
/ˈsēhôrs/
The text in bold here is what you're looking for when you want to find the "Phonetic Transcription." Hope this helps!
