your current income is below level (projected to full calendar year) and you don't have to pay any income tax.
However, if your income increase and your total income for the year is higher than the estimated amount used, then you may have to pay taxes to cover the shortfall.
e.g. if you have 20 hours X $16 = $320 for two weeks.
Then your projected income is $320 X 26 pay periods = $8,320. With that income level, you don't have to pay any tax.
However, if your total income for the full year is actually $35,000.Then you have to re-calculate income tax for the full year. Assume proper amount of income tax was remitted for the other employment income, then your $320 (no tax) may be subject to additional tax when filing your 2023 T1 tax returns.