Fishing line, thread, and wire are usually wound around a special cylinder called a spool. If you enjoy sewing, you might buy spools of colored thread at the crafts store.
Back in the days of cassette tapes, the magnetic tape would occasionally get tangled in the tape player and have to be wound back on its spool. You can use this word as a verb, too: "Will you spool that loose thread back on the bobbin for me?" Computer experts use spool to mean "store data temporarily," so they might spool computer files to a desktop folder, for example.