To be precise and vague,
Data is something which tells us about something.
For example, ‘Red’ is not Data; But when associated with an entity ‘Apple’ that is to say “Apple is Red” it is now a data about our entity Apple.
‘0108IT091041’ may seem vague or an arbitrary string generated but when I associate it with a student saying that it is a Student’s ID it becomes data.
Science is the art of knowing.
Knowing What, Why, How, Where, When etc. etc. etc. is Science.
Knowing the properties of any entity, or why it is so is Science.
And it is important.
It is important because only after knowing any property(ies) of an entity can we properly use it in next step.
That is to use it to our benefit.
Only when we knew how to make fire, control it etc. could we use it to our benefit.
Knowing the principles of gravity has takes us so far (quite literally).
To sum up!
Data science is the art of knowing properties of entities, there data, relations between different data, how a change in one can affect other, how can we find missing values or deduce something which wasn’t there already from what we are given.
Then we can do cool magic tricks with data science, just as Sir Galileo did by throwing down two different masses from the Leaning tower of Pisa and they ‘magically’ fell together!