Contention Ratio: This one measures the number of users who are sharing a fixed amount of internet bandwidth in a location at the same time. So if the contention ratio is very high then your speeds can be affected. The contention is considered important because internet service providers often put in a lot of 'assumptions' about their customers.
Let think 20 people in an area have opted for a 2Mbps connection. So that is a 40 Mbps bandwidth. Now telecom providers will assume that not every user would be accessing the internet at the same time. So instead of 40 Mbps they might provide a 10 Mbps bandwidth since 'not everyone is using the internet at the same time'. When you look at it now if all 20 users access the internet at the same time then the guaranteed speed is not 2 Mbps but 500Kbps.
The reasoning being assumed here is that bandwidth is a scarce resource and hence should be allocated in this manner so that the prices can also be kept low. Think of it like this now. You go to a hotel and order a room for 1000 for yourself. When you get to the hotel you find that you have to share the room with another guy because supposedly, the hotel rooms are a scarce resource during the peak season. But not to worry you will get the room for yourself when he goes out for shopping or sightseeing or what not. Now isn't this great.
As of now contention ratio are not disclosed by internet providers. If these are disclosed then users would be able to choose their providers more carefully. This would also put pressure on internet service providers to put more pressure on their quality of service.
Latency which is the delay a user feels when trying to access the internet. If your service provider gives low latency then you would be able to access the internet faster.