Consider German:
In both of these, der Mann stands in the "der" or "nominative" case, while der Knabe stands instead in the "den" or "accusative" case. This kind of system is called a "nominative-accusative" system, or an "accusative" system for short. This is the kind of system English has, insofar as it has anything.
Now consider Basque:
In Basque, gizon is "man," mutil is "boy," and a suffix -a is "the." Notice that gizon is different depending on whether it is the subject of a tranistive or intransitive verb. The first form is the [absolutive case]? and the second form is the ergative case.
English does show a trace of ergativity. With an intransitive verb, adding the suffix "-ee" to the verb produces a label for the person performing the action:
However, with a transitive verb, adding "-ee" does not produce a label for the person doing the action. Instead, it gives us a label for the person to whom the action is done:
The differing effect of the "-ee" suffix, depending on the transitivity of the verb, can be considered ergativity.
Compare nominative case, [absolutive case]?, accusative case, dative case, genitive case, vocative case, ablative case.