HELP what does *k1, slide off the needle yo* mean?

The pattern is a diagonal knit scarf…cute, fun and … ait of a difficulty
the row before calls for
k1, yo
next row
k1,slide off the needle yo

These are the 2nd and 3rd rows in a lace pattern of five rows… to complicate mattters further there are a derease and increase at the beg and end of every other row… to form the diagonal shape of the scarf…
Please help! Thanks to any and everyone[FONT=“Arial”][SIZE="5
Bridge
The pattern is for the Balck and White Diagonal Striped Scarf from www.mylittlecitygirl.com
the stiches I need help with are from the Lace Pattern portion… found at the top of page 3…Rows 3 and four

On the 2nd row you drop the yo from the previous row off the needle.