Note that the field layout also depends on whether the batsman is left or right handed. The diagram
below is for the (admittedly
more common) right handed individual
, where the off side
is to the batter's right. For a leftie, the field would be a mirror image, so the slip fielder(s) would still be nearby and at about a 30 degree angle to the stumps, but they would be on the other side of the field.
Additionally, "square" means perpendicular to the pitch whilst "fine" suggests further around towards the keeper - so someone fielding, say, three lines down the diagram from SL (Square Leg) would be at fine leg.
It is also common to have more than one slip and there are defined positions for each of "first slip" through fourth slip. This means you can end up with fielders at first and third slip with a gap between them where second slip would be.
Of course, on side and off side have no rules associated with them as they would in most football sports. The on side is often called the leg side.