A float is when a needle in the knitting, does not knit in a row. The needles on either side of the float will knit, and the needle that is creating the float will not knit while holding the loop from the previous row.
Float
A float can be multiple stitches wide, and you only need one knitted stitch before starting the next float. On Kniterate, a float can be up to 5 or 6 stitches.