Est means "is" or "are" in French, while c'est translates to "it is", "this is", or "that is". C'est is a contraction of ce est, ce meaning "this" "that" and/or "it", and est meaning "is" (as stated above).
Some examples in sentences:
C'est très drôle. - "This/That/It is very funny."
C'est complètement correct. - "This/That/It is completely correct."
Tu est prêt. - "You are ready."
Il est fatigué. - "He is tired."
However, despite est translating to both "is" and "are", c'est never means "those/these are"; the correct form is ces sont.
Ces (chaussures) sont sales. - "Those (shoes) are dirty."