u/No-Victory4474

I’m in my late 30s and recently decided to get into sailing. I bought a small sailboat two years ago, but it’s been sitting in my yard until now. I’m planning to put it on a nearby lake soon.

While replacing the engine, I noticed that one of the lines on the mast is badly frayed and probably needs to be replaced. The problem is: I don’t actually know what this line is called or what its purpose is.

Can anyone identify it and explain what it’s used for?