An action, or an instance of an action.
French ‑ation or Latin ‑ation‑.
The New Oxford Dictionary of English records more than 1,400 nouns that contain this suffix. Most are associated with verbs, commonly those in ‑ate (see ‑ate3): creation, deviation, moderation, navigation, perforation, pronunciation, resuscitation, suffocation, vibration. Others are associated with a variety of verbs, all ultimately from Latin: application with apply (Latin applicare); probation with probe (Latin probare, to test or prove); publication with publish (Latin publicare, make public).
Many other words in ‑ation appear to derive from English verbs: alteration, consultation, embarkation, formation, plantation, taxation, temptation, vexation, visitation. Though this is accidental, as the English verbs and nouns can all be traced back to Latin sources, this apparent connection was important in developing the idea of ‑ation as a true English suffix, so permitting nouns like flirtation to be based on English verbs. However, a number of nouns in this ending do not have an associated verb in English: duration, tribulation, ostentation, constellation.