K to last stitch

Hi I am a beginner and I would like to ask something.

What does this mean?

Row 6: K1, m1, k to last st, m1 k1 (15sts).

I don’t understand about k to last st.

Thank you so much for helping me.

That’s exactly what you do-you knit till you get to the last stitch there you will m1 which means make one and then knit the stitch.