I am creating my tax profile and it say,"Did you have expense related to your employment?" Is this something related to flat $2 or something else?

The expenses related to employment is about any kind of expense you incurred on your job.  Some employers require their employees to pay for their own expenses that can be substantial. Or use their own vehicles or tools at work. These kind of expenses are employment expense, which could be claimed when filing tax return. For more information please see our TurboTax FAQ : Can I Claim Employment Expenses?

However, if you work from home then you would have some expenses related to your flat known as home office expenses. For example, workspace-in-the-home costs such as internet, electricity, heat, etc. if your job requires you to maintain a home office. 

As per the GST370 rebate, the blue link in your return explains:

If you're claiming employment expenses, you may be able to claim a rebate of the GST or HST you paid on them.

As an employee, you may qualify for a GST/HST rebate if:
 

• you paid GST or HST on certain employment-related expenses and deducted those expenses on your income tax and benefit return; and
• your employer is a GST/HST registrant.

You don't qualify for a GST/HST rebate if your employer:
 

• is not a GST/HST registrant; or
• is a listed financial institution.

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