A very cute pc.
There are no sound outputs on the back panel.
I think the pc was designed to use the front audio with headphones.
If your monitor has speakers, hdmi should be able to direct sound to them.
Normally monitor speakers are crummy sounding.
If you have a speaker set with a green cable, I think you could plug it into the front instead of headphones.
Here is one product I found that might serve: https://www.amazon.com/Optimal-Shop-External-Channel-Surround/dp/B00Q4WQ7XW