Is there a place to enter my business supplies/office supplies/supplies for the purpose of conducting business?

If you are sole proprietor /Self employed you have to complete the form T2125 listing out all your income and expenses incurred for the purpose of running your business. 

When you prepare your tax return, you will just enter all of your business’s details (income and expenses) into the self-employed section of TurboTax Self-Employed.

All the business-related information is entered into the T2125, Statement of Business Activities, which informs the CRA of your self-employment income and deductions as well as deductions.

The T2125 is sent to the CRA along with your other tax forms which make up your T1 General return.

If you own your unincorporated business with a partner (or partners), the same T2125 is filled out, however, there is some additional information relating to the partners which is required, and TurboTax Self-Employed takes care of that too.

For more information visit:

https://turbotax.intuit.ca/tips/filing-taxes-as-a-small-business-owner-6214#:~:text=All%20the%20business%2Drelated%20information,deductions%20as%20well%20as%20deductions.