Loss is something that you need to be worried about logarithmically. 1% of loss really doesn't matter and all circuits will show something like this. However 10% of loss will dramatically reduce your data throughput to somewhat less than 50%.
Latency is delay and it depends on what you are doing. Variable latency (jitter) is more of a problem than latency itself in most situations. For most traffic, latency under 200ms doesn't cause issues, we have regular video conferences from the UK to the west coast of the US and SA, in both cases latency approaches 200ms but they work just fine. However VDI has a much lower tolerance of latency and anything over 20ms causes noticeable response issues. Finally traffic like file transfers doesn't care at all!
Hope that helps