tl;dr: Manny can make 4 bookmarks.
Hello!
So, Manny has 1/2 yards of fabric, and it takes 1/8 yards of fabric to make a bookmark.
The total amount of bookmarks Manny can make is 4.
When you do 4 · 1/8, you'll see that it gives you 4/8, or 1/2 simplified. This is all of the yards of fabric Manny has.