It is slang for 'about', 'roughly' or 'approximately.' A person may say it if they are not exactly sure of the time of an event.

thank you very much :) it's intersting

When used correctly, "ish" is actually a suffix meaning "having the quality of whatever the root word happens to be". Things that are reddish, have a red quality. amateurish means to be the product of an amateur. dryish mean not completely dry but almost. Almost any adjective can be converted by adding the ish to its end. People have taken to using it in place of approximately. Noonish = around noon. 11 ish = around 11.