Loose active stitch - new knitter

Hi. Newbie knitter here. I taught myself the knit stitch. I know learning tension will take time. I’m okay with that. Lately, I’ve had one lose active (on the needle) stitch. It would be at the end of the row. Any way to tighten that up? Thank you.

How do you do the border? Do you slip or knit the first stitch? If you slip, remember to tighten it a bit after slipping.

Thank you.