I added some episodes of Walden Pod to my comment, so check those out if you wanna go deeper, but I’ll still give a tl;dl here.

Privacy of consciousness is simply that there’s a permanent asymmetry of how well you can know your own mind vs. the minds of others, no matter how sophisticated you get with physical tools. You will always have a different level of doubt about the sentience of others, compared to your own sentience.

Phenomenal transparency is the idea that your internal experiences (like what pain feels like) are “transparent”, where transparency means you can fully understand something’s nature through cognition alone and not needing to measure anything in the physical world to complete your understanding. For example, the concept of a triangle or that 2+2=4 are transparent. Water is opaque, because you have to inspect it with material tools to understand the nature of what you’re referring to.

You probably immediately have some questions or objections, and that’s where I’ll encourage you to check out those episodes. There’s a good reason they’re longer than 5 sentences.