Cast on with 3 strands of yarn

I have this pattern that starts off with “Cast on 5 stitches with 3 strands of yarn.”(slippers are all one color and I am starting at the toe end) I am making these French Press Felted Slippers, and I haven’t heard of a 3 string cast on. I have no clue how to do it. Help!
Thank you

All you need to do is hold 3 strand of yarn together. Tis all.

Most of the time a pattern calls for a single strand but sometimes it might ask you to hold 2 or 3 pieces of yarn together to knit with.

Merry Christmas!!

Most of the time a pattern calls for a single strand but sometimes it might ask you to hold 2 or 3 pieces of yarn together to knit with.