Help understanding pattern instructions

Dec 1 St at each end of 15 foll alt rows.

I Can’t work this out. Can someone please explain.

Welcome to the forum!
Decrease one stitch at each end of the row. That’ll be 2sts decreased per decrease row.
Dec every other row so on rows 1,3,5,7,9 etc until you’ve completed 15 dec rows (30sts decreased).

Thank you so much for promptly answering my question