Window balance or sash
Hi there!
I'm afraid we won't be able to make an identification without seeing the original hardware. There's simply too many options and we need something to go off of to help narrow down some options. Is there an identical window in the house? If there is, remove an undamaged balance and show us. I may need more photos and info after that, but I have to know what to ask for first. Just something to keep in mind.
The part is missing...I'm hoping you can identify the balance, or is there something else we can install
This looks like a clip used with coil balances. There should be a pivot shoe below the coil springs that we'll need to see in order to identify what hardware you need. Take a look at the videos I've attached below and let me know if this helps.
