Don't confuse itemized deductions on schedule A with your business expenses/deductions on schedule C. They are separate. For Schedule A personal deductions, you get to take your itemized deductions or the standard deduction, whichever is larger.  Itemized deductions are things like Medical, Gifts to Charity, State Income Taxes Paid, Mortgage Interest, Property Taxes, Car Registration fees, etc.

You get to take both,  your business expenses AND the Standard Deduction (or your personal Itemized Deductions).  And you have to enter your business expenses.  Be aware, if you have self employment income you can get in trouble for not reporting all your expenses to qualify for the EIC.

It depends on a couple things:

If your business expenses are "job related expenses" meaning they are unreimbursed from your W-2 employer, those expenses are not deductible in 2018.  The Tax Cuts and Jobs Act of 2017 suspended the miscellaneous deductions that were subject to the 2% floor on the federal return for the years 2018 to 2025.  Some states still allow the deduction for job-related expenses, therefore they can still be entered into the federal return and TurboTax will determine if they can be deducted on the state return.

If your business expenses are for a self-employed business, then those are deductible whether you itemize or take the standard deduction on your return.  See the FAQ for entering self-employed business expenses on Schedule C in your return.

https://ttlc.intuit.com/replies/5802554