Sounds like the border on a blanket or square. Picking up the stitches is a way of putting live sts onto the needle from the knit fabric. There's a video here
to show how. You're to pick up 60sts along each side, placing a marker at each corner and a different color marker at the last corner to mark the beginning of the round. There'll be 240sts total on the needle when you're finished picking up sts. You can mark out the halfway or quarterway points on each side to make it easier to pick up the sts evenly if that helps.
But perhaps there's something else that is puzzling you?