Welcome to the community!
While Fido does offer a temporary suspension for eligible lines, as far as I am aware, the option is only for 2 to 12 months (see here). I do not believe you would be able suspend your account for more than 1 year.
One option for keeping your phone number for an extended period would be to transfer it to a pay-as-you-go service. Depending on the service, you would have to regularly top-up the account to keep it active, though. However, you should note that upon return, your current plan would likely not be available anymore.
If you're eligible for the temporary suspension and you decide it suits your needs, you would need to contact customer service to have it set up. Alternatively, you might consider sending @FidoSolutions a PM. Once they verify some information, they will also be able to access your account.
Hope this helps 😀