These are the espionage point you have invested into that civ vs what they have invested into you. Bigger numbers are better in theory but outside special strategies it's not worth investing espionage points to improve the ratio. Just ignore it. You can focus all of your espionage points into one civ to keep up with a key opponent and ignore the others.
Espionage points invested into a civ give you passive information about that civ if your ratio with them is favourable or at least at an acceptable level, like their production/food/gpt/power graphs, what they are researching and if you have a lot invested into them.
