Assets must generally be depreciated over time. An asset is any property that has an expected useful life of more than 1 year. The asset is listed with the business when it is placed in service. Very generally, if the asset has an expected life of 5 years, for example, you deduct 1/5 the cost each year over 5 years.
There are some exceptions. You may be able to use "Section 179" depreciation or "bonus depreciation" to take the entire cost all at once, however, if you stop using the van for business before the end of the normal depreciation period, you have to pay back the depreciation you are no longer entitled to.
If you simply list the van in Turbotax, the program will tell you what options are available.
We also have to be careful about other factors you haven't mentioned. The rules are different if this is a personal vehicle used less than 50% for work, more than 50% but less than 100%, or 100% for work. There are different rules if the vehicle is more or less than 6000 pounds gross weight. You also have to consider whether you want to track all your expenses (gas, repairs, maintenance) or use the standard mileage method, that affects how you claim depreciation.
Everything is discussed in chapter 4 of publication 463.
https://www.irs.gov/forms-pubs/about-publication-463
