To answer your other question, first-- unless the pattern says otherwise, each square is a stitch, so you read from right to left on the knit side, and from left to right on the next row for the purl side.
Yes, you can fix this. Do you know how to let a stitch drop and then let it ladder down to the mistake? If so, then do that, then take the white bar of yarn between sts on the back, and with a crochet hook, let the black yarn drop and pick up that bar and make a white stitch. Then with the crochet hook, re-knit that line of sts all the way back up to the top. There is probably a video about fixing mistakes here on this site which might show you how to do the crochet hook thing.