The dash (тире) in Russian is a very complicated topic, difficulf for many natives. There is a lot of rules and specific uses, but in short, the dash is used: 1) to separate subject from predicate when both are nouns: Его друг -- учитель. 2) to separate subject from predicate when subject is a noun and predicate is an infinitive or both are infinitives: Его работа -- учить людей. 3) to separate two sentences when the second sentence is a result or consequance of the first one: Пришел учитель -- сейчас начнётся урок. 4) before a generic term following an enumeration: Ни английского, ни испанского, ни китайского -- ни одного из этих языков я не знаю. Here are more rules (in Russian): http://new.gramota.ru/spravka/rules/23-spravka/rules/158-tire