Latin for "With this, therefore because of this".
Two events that occur together in time, space, or otherwise, need not be causally related, and in particular, colocation does not imply which one is cause and which one effect. Even if normally one type of event causes another, it is only an assumption to assert cause and effect.
For instance, if a man shoots a gun in a crowded room, and someone falls down, it doesn't mean that the gunshot hit the person, causing the fall. There could have been another gun, or the fall could have been in reaction to the noise, or the person could have tripped over the dog.
See also post hoc ergo propter hoc.
Both are special cases of non causa pro causa.