A scale of 1:5000000 means that:
This is mainly used in map or shadow etc. things.
For example in map it is given that the scale is 1mm:5000000mm, then it means that 1mm on the map is equal to 5000000mm in real life. So, you can be asked what does 5mm on map means in real life. So, you have to solve like this:
5 × 5000000 = real life size
25000000mm = real life size
In shadow like question, it can be asked that if 5000000 m of building casts a shadow of 1 m, then how much will be the shadow of a 10000000 m building. So, you have to solve it like this:
(10000000/5000000) × 1 = shadow size
=> 2 × 1 = shadow size
=> 2m = shadow size
You can tell me the specific questions so that I can help.