It depends on the industry, but in most cases, you do not have to pay for your company uniform.
In most cases, an employer will provide you with a uniform that must be worn during work hours. This can be a polo shirt, a jacket or blazer, or even a specific type of shoe or socks. If you are required to wear any of these items outside of work hours, such as at a school function or on the weekends, your employer will usually reimburse you for those costs. However, if they don't offer reimbursement, you probably only need to pay for the items that are required to be worn during work hours.
Some employers do require their employees to purchase their own uniforms and then reimburse them based on mileage and/or hours worked. In this case, it is important to check your paycheck regularly so that you know exactly how much money has been deducted from each paycheck and what it was used for (e.g., gas money).