It just means you need to figure out how to route between them, that’s all.

Oh, they just left you some extra patch cables? That was nice of them.

The wavelength of the fiber might be printed on it. I know some fibers are color-coded based on their wavelength, but I don’t know if it’s universal.

You’ll need to match the modules to the fiber.

There definitely are optics available for single mode. The problem is that the wavelength will need to match what you are being sent from your provider. So we can’t really answer your question, you will have to ask them.

1310nm is quite common but we can’t assume your link is 1310nm.