As Tarrantella said, each chart has a key that tells you what the symbols mean.
If you're working back and forth, right side rows are read right to left and wrong side rows are read left to right. Sometimes a chart doesn't even include the wrong side rows if they're just purled.
Each square represents a stitch or the result of working a stitch. For example, if you see the symbol /, it usually means to knit 2 together. It only takes up one box because after you do the k2tog, you have 1 stitch left.
It helps to block off all the rows above the one you're working on--I use Post-it notes.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog
IngridKH on Ravelry