Explain how an ionic compound such as sodium chloride dissolves in water.

Water is polar and so is attracted  to the δ+ and δ- regions of an ionic compound such as sodium chloride

water  molecule:       O δ-
                                l   l
                        δ+  H   H δ+

water in an endothermic reaction (uses energy) breaks the strong ionic bonds between the ionic compound and surrounds the ions with hydration shells

so the Na+ ion will be surrounded by water with the Oδ- of the H2O touching the ion

and the Cl- ion will be surrounded by water with the Hδ+ of the H2o touching the ion

and that is how water dissolved ionic compounds 
water is polar so it can dissolve any polar substance (like dissolves like)

hope that helps

True, the standard unit for volume is liters which can be represented by either a lower case "l" or a capital "l"