Learn Russian: Банк слева. - The bank is on the left.

In Russian, the verb "to be" is almost always left out in the present tense. You just put the subject (Банк) and its location (слева) right next to each other to say it "is" there.

In English, "on the left" is three words, but here it's just one (слева). Why?

Слева is a single adverb that means "on the left" or "from the left." You don't need a separate preposition for "on" in Russian for this phrase. It's best to memorize слева as a fixed directional word.

How do we know it's "The bank" and not "A bank" if Russian doesn't have articles?

Russian doesn't use little words like "the" or "a." Instead, word order gives us a clue. Putting Банк at the start of the sentence establishes it as the known topic we are talking about, which usually translates to "the bank" in English.

What happens if I switch the word order and say Слева банк?

You can absolutely say that! However, Russian uses word order to show the main point of the sentence by putting the most important new information at the end. Банк слева answers "Where is the bank?" (It is on the left). Слева банк answers "What is on the left?" (There is a bank).