Remember that in sentences it is/they are ... + article/determinant (un, une, le, la, les, des...) + noun/pronoun, you will use c'est or ce sont instead of il/elle est or ils/elles sont.
See C'est vs il/elle est: Saying it is
Now look at these examples:
Est-ce ta trousse? - Oui, c'est la mienne.
Is this your pencil case? - Yes, this is mine.
À qui sont ces livres? Ce sont mes livres.
Whose books are these? These are my books
Note that ce is used with the verb être as follows: in its singular form, c'est, means it is /this is /that is, and in its plural form, ce sont, means they are /these are /those are.
Both forms are used to refer to a thing or a person (i.e. a girl, a table, a house, ...), and they agree in number (singular or plural) with the thing they refer to.
BUT
When c'est is followed by an adjective or an adverb on its own, you NEVER use ce sont, even if the thing referred to is plural:
C'est pratique, les ciseaux.
They're practical, scissors.
Et leurs anniversaires ? - C'est bientôt !
What about their birthdays? - They're soon!
Note that if c'est is followed by an adverb AND a noun, then the noun is the one that matters!
ATTENTION:
It is worth noticing that the first rule is not always followed rigorously by French speakers. You could indeed hear them using c'est when they should use ce sont:
However, they will never use ce sont for c'est !
Learn more about these related French grammar topics
Examples and resources
Et leurs anniversaires ? - C'est bientôt !
What about their birthdays? - They're soon!
Ce sont bientôt les vacances!
It's almost the holidays!
C'est pratique, les ciseaux.
They're practical, scissors.
C'est ma maison.
This is my house.
Ce sont mes maisons.
These are my houses.
Ce sont les amis de mon frère.
These are my brother's friends.
À qui sont ces livres? Ce sont mes livres.
Whose books are these? These are my books
Est-ce ta trousse? - Oui, c'est la mienne.
Is this your pencil case? - Yes, this is mine.
C'est bientôt les vacances!
It's the holidays soon!
Q&A

Cécile
Kwiziq language super star
27/06/18
Hi Maria,
You could say:
"J'utilise ces tomates, elles sont très mûres, ce sont les dernières de la saison."
(I am using these tomatoes, they are very ripe , the last ones of the season.)
You cannot say, elles sont les dernières de la saison.
Hope this helps!
ch
Kwiziq community member
28/09/18

Cécile
Kwiziq language super star
26/06/18

Aurélie
Kwiziq language super star
18/04/18
Bonjour CrystalMaiden!
The answer is no, you would never say "ceux sont" in French :)
Bonne journée !

Ron
Kwiziq community member
21/10/17

Ron
Kwiziq community member
17/10/17
Cheryl
Kwiziq community member
18/10/17
Chris
Kwiziq community member
19/10/17
-- Chris. (not a native speaker)

Gruff
Kwiziq language super star
20/07/17
/revision/grammar/when-to-use-cest-or-il-est-elle-est-to-say-it-is
When referring to a specific person, you always used "C'est...".
Hope that helps.

Aurélie
Kwiziq language super star
10/02/17
Susan
Kwiziq community member
12/02/17

Aurélie
Kwiziq language super star
20/12/16

Aurélie
Kwiziq language super star
14/10/16
/revision/grammar/when-to-use-cest-or-il-est-elle-est-to-say-it-is
Please have a look at it, and let us know if you're still struggling with this concept, and what bothers you specifically, and we'll be happy to try and clarify it for you :)
À bientôt !
Heba
Kwiziq community member
23 September 2018
1 reply
Confused
Bonjour,
In the examples on the right you say in number 4 on the second row:
C'est bientôt les vacances!
It's the holidays soon!
But in explaining the lesson you say:
Ce sont bientôt les vacances!
It's the holidays soon!
Which is correct?!
Thank you.
Chris
Kwiziq community member
24 September 2018
24/09/18
Hi Heba,
Both are acceptable, although the plural version "ce sont" is more formal and considered a bit more "proper".
Here is a page that explains it well: http://www.oniris.be/forum/c-est-les-vacances-ou-ce-sont-les-vacances-t6977s0.html