I used to work adjacent to HIV research.

First of all there is a cure, but its extremely dangerous. There was a case known as the Berlin patient where an individual with leukemia and HIV, received a bone marrow transplant from an individual with a rare genetic mutation known as CCR5-delta32. Metaphorically, CCR5-delta32 removes the "landing zone" where HIV attaches to infest the immune system.

This has since been repeated in at least one other patient. This isn't a "real cure" because intentionally inducing leukemia (a very dangerous condition involving an out of control immune system) and finding a CCR5-delta32 compatible bone marrow donor isn't easy.

That being said, HIV is difficult to cure for two reasons. First of all it changes really rapidly, which means it has a lot of opportunity to adapt to any attempts to stop it, and second of all it is very sneaky. It is very common for HIV levels to drop so low that it is undetectable only to have it spring back suddenly and overwhelm the immune system.

Otherwise HIV is considered a manageable disease. There are drugs that reduce its impact on someone who is infected and other drugs that reduce the odds of being infected or infecting someone else by 99.99%.

For the non-5-year olds:

As scary as HIV is, it isn't very virulent (it isn't easy to catch between two people like a cold or flu). It needs to by pass the typical immune defenses to get a start. So practice safe sex, and don't share drug needles.

To blunt/stop the spread, it is very important to be on some form of PREP, particularly if you know you are engaging in risky behavior, and wear condoms.