【JLPT N5★だ / です (da / desu): to be (copula)”】
Meaning: to be (copula)
Formation:
Present affirmative: だ (plain); です (polite)

A copula is essentially a verb meaning “to be”. It can be used to show identity (Max is a dog), properties (furry), state (happy), and membership in a set (one of my pets). Other verbs, like “become”, “seem”, “feel”, and “appear”, also function much like the main copula.
Forms of “be” English include “is”, “am”, “are”, “was”, “were”, “been”, and “being”. The Japanese copula also has several forms, the most important of which are the plain form だ “da” and the polite form です “desu”.
Note that while the English “to be” can also be used to show existence (I am in my living room), Japanese has two separate verbs for this purpose: いる “iru” for animate objects (animals, people, robots) and ある “aru” for inanimate objects. You’ll learn how to use these verbs later on.
The Copula “Desu” (Japanese Professor)

 
日本語 / Japanese
(1)妹は学生だ / 学生です。
(2)弟は医者だ / 医者です。
(3)私はアメリカ人だ / アメリカ人です。
(4)天気は晴れだ / 晴れです。
(5)天気は雨だ / 雨です。
(6)天気は曇りだ / 曇りです。
 

 
英語/ English
(1)My younger sister is a student.
(2)My younger brother is a doctor.
(3)I’m an American.
(4)The weather is sunny.
(5)The weather is rainy.
(6)The weather is cloudy.
 
ひらがな / hiragana
(1)いもうとは がくせい だ / がくせい です。
(2)おとうとは いしゃ だ / いしゃ です。
(3)わたしは あめりかじん だ / あめりかじん です。
(4)てんきは はれ だ / はれ です。
(5)てんきは あめだ / あめ です。
(6)てんきは くもりだ / くもり です。
 
Roman Alphabet
(1)imouto wa gakusei da / gakusei desu
(2)otouto wa ishada / isha desu
(3)watshi wa amerika jin da / amerika jin desu
(4)tenki wa hare da / hare desu
(5)tenki wa ame da / ame desu
(6)tenki wa kumori da / kumori desu