It's a "tilde."

The official name is virgulilla, but the most of Spanish people don`t know it. http://es.wikipedia.org/wiki/Virgulilla

Called, is a regular verb, the infinitive is "Call" and the mean (i'm going to show you with examples) i very common to use call or called (for actions in the past) when you use the phone or cellphone - i called my mom this morning with my cellphone. (the action is to "talk" with somebody) Also you can use called or call when you refer to names or nicknames: - my friends call me Jones. - my frineds called me with the nickname "Chubaka"