Number in brackets at the end of each row indicates the number of total stitches for that row.

Each bobble stitch will have one single crochet when you make rounds of Sc above it, so your stitch count remains the same for each row.

In this project, heart bubbles on the sleeves have been made using another color to add accent, you can either do it in same color so it matches the whole sweater, or you can do it with your secondary colour just like shown in the picture.

To do bubble in another color, you will have to change color on the stitch before each bubble stitch and change color back to main color before you close the bubble, when you have 5 loops on your hook.