A scalar quantity only consists of a number; however, a vector quantity consists of a number and a direction.
A example of a typical scalar quantity would be temperature. We might say that the cup of tea is at 80 deg C with no direction specified. What we can't say is that the temperature of the tea is 80 deg C due north- it simply makes no sense! Other scalar quantities include: time, density and volume. Equally, none of these makes any sense when you specify a direction to it. Saying the time is 1.30 pm due east makes no sense either. So the temperature of the atmosphere can go up and down in value but adding a direction is not appropriate.
In contrast, an example of a vector quantity would be force. A force has a number part and a direction too. This is because the action of the force on an object depends not only how strong the force is (the number part) but also in what direction that force is applied to the object. If I have a book on a table and apply 10N directly downward then all I do is help push it harder onto the table surface. However, if the same force is applied to the side of the book, then disregarding friction, it will slide along the surface of the table, an altogether different result. So here the direction does have a meaning as the outcome is different depending on the direction that force is applied.