What does a 2:1 ratio mean?

Hint: 2:1 ratio means that we have divided two quantities and the result of the simplification of the result of division will give us 2 divided by 1 and we can write ratio in place of division sign. This ratio is also telling how many times one of the quantities is that of the other quantity.

Complete step-by-step solution:
In the above problem, we are asked to find the meaning of the 2:1 ratio.
We know that ratio means the simplification of the division of the two quantities. And 2:1 ratio means when we divide the two quantities then the division of two quantities is in the form of 2 divided by 1
Let us explain what we have just said by an example say, we have two quantities say 40 apples in the one basket and 20 apples in another basket then when we divide the apples in the two basket we get,
$\Rightarrow \dfrac{40}{20}$
On simplifying the above expression then one zero will be cancelled out from the numerator and the denominator and we get,
$\dfrac{4}{2}$
Also, the numerator and the denominator will get divided by 2 and we get,
$\dfrac{2}{1}$
And we can convert the above division into ratio by writing ratio symbol in place of division sign and we get,
2:1
This is how we have defined the ratio 2:1.

Note: The other way of understanding 2:1 ratio. For e.g., suppose we have given two sets of pens. Let us name the two sets as A and B then when it is given that the number of pens in the two sets is in the ratio of 2:1. This means that set A has 2 times more pens than set B has.