In aSc, go to > Teachers (or Students/Subjects). Select the rows you need and use Ctrl+C . Paste directly into Excel 2021.
Some users mean "ASC" as in or a specific piece of software that outputs binary .asc files. Excel 2021 does not open binary ASC files natively, but you can use a VBA macro if the file is actually a text file with an .asc extension. asc timetables to excel 2021