Bubble pattern

I don’t understand this can anyone help please?

Special Abbreviation
K5B (Knit 5th st Below) - slip next st off left-hand needle and drop 4 rows down. Insert point of right- hand needle under strads and into the st on the 5th row down, insert left-hand needle under the strands and into the stitch. Knit the st normally catching the strands at the same time.

Welcome to KH!
This seems like the clearest video for the bubble stitch. The numbers may be different from those in your pattern but the idea is the same.

Thank you so much. All makes sense now. Have a lovely day.

Thank you so much, all makes sense now. Have a lovely day.