Okay, imagine that you have a lemonade stand and you want to sell shares of your lemonade stand to other people so they can be part owners too. This is called "going public" and it usually means big companies that everyone knows like McDonald's or Nike are selling shares to regular people like you and me.
But sometimes, instead of selling shares to everyone, big companies will sell shares to only a few rich or important people. This is called "private investment in public equity" or PIPE for short.
It's kind of like if you invited only your best friends to invest in your lemonade stand instead of selling shares to anyone who wants to buy them. Private investors usually have a lot of money and they might be able to help your lemonade stand grow faster because they have connections or know a lot about business.
But sometimes, private investors can also take advantage of the lemonade stand owner by buying shares for less money or making rules that aren't fair for everyone. So it's important to be careful and do lots of research before letting private investors in.