As a Verb or Adjective: 1. To be located on a surface. English = (be) on. 2. To put something on a surface; to lay something on a surface; to place something on a surface. 3. To be located or situated at a place. English = (be) at. As Modifier: 1. Used to re-introduce a topic of discussion. English = about, with reference to. 2. Used after many verbs (especially 'talk', 'write' and 'think') and before a noun to mean that the topic of the activity is the following noun. English = on, about, concerning, pertaining to.