The main point:
です・だ means 'to be.' It is commonly translated as 'is' or 'am' in sentences.
The longer explanation:
です and だ are linguistically referred to as the 'copula.' Basically, this means that they work as the verb 'to be', although it's not exactly the same as it is used in English.
Unlike English, the copula basically goes at the end of the sentence in Japanese. Verbs usually go at the end of the sentence in Japanese.
Remember that です is the formal way to say it, and だ is the casual way.
だ is often omitted from the sentence entirely! So instead of saying 元気だ (げんきだ, I am good), many people will just say 元気 as a complete sentence!
Some say it gives a sentence more of a "masculine" tone. Be sure to listen to native speakers to get the hang of when you should use it!
Click for Hiragana げんきです。
Click for English translation I am good.
小林です。(I am Kobayashi)
木だ。(It is a tree.)
|でございます||Very formal (Teineigo)|
|である||Casual (but not used in conversation)|
*Items in green will be taught later or do not appear on the JLPT.