"We are ready!"
Translation:Vi er klare!
When not used in an expression, the adjective should be agreed: Jeg er klar, Dere er klare. In an expression, you normally do not: Jeg er klar over det, Er dere klar over det? (være klar over noe); Gjør deg klar!, Gjør dere klar! (gjøre (seg) klar). Most people, however, would not consider it wrong if you did: Er dere klare? is okay.
Vi spiser is we are eating using the present verb form of eat (å spise). Vi klare is not correct because it is saying literally "we ready" and klar (the singular form) i believe is an adjective in this sense and not a verb. The verb is er, the present tense of å være which is to be.