Refer to the following link for all the info you need about applying for a citizenship.
http://www.cic.gc.ca/english/citizenship/become-eligibility.asp
Here's a quote from the above link:
"If you are between 18 and 54, you will have to send proof of your ability to speak and listen in English or French with your citizenship application.
Some examples of this proof can be:
The results of a CIC-approved third-party test; or
Transcripts or a diploma from a secondary or post-secondary education in English or French, in Canada or abroad; or
Evidence of achieving Canadian Language Benchmark (CLB)/Niveau de compétence linguistique canadien (NCLC) level 4 or higher in certain government-funded language training programs."