Other answers say that you need a B-1/B-2 visa, but this is not precisely true. As a business visitor, you will be in B-1 status as a "visitor for business." B-2 designates the closely related status of a "visitor for pleasure," which covers tourism and visits to family and friends, for medical treatment, and for most other purposes that are not related to business.
To be admitted in B-1 status as a business visitor, you need a B-1 visa. The State Department usually, but not always, issues the visa as a B-1/B-2 combination visa, which allows you to be admitted in either B-1 or B-2 status.
It seems that the State Department is more likely not to issue a combination visa when the reciprocity terms for business and pleasure visitors are different. You can see at https://travel.state.gov/content/travel/en/us-visas/Visa-Reciprocity-and-Civil-Documents-by-Country/Belarus.html that they are not different for nationals of Belarus, so you will probably get a B-1/B-2 visa, but you might get a B-1 visa. Either is fine for this trip.
Visitor visas for citizens of Belarus are valid for no more than one year, so if you know that you will make a separate non-business trip to the US within one year of your application, you can ask specifically for a combination visa. Otherwise, it doesn't matter whether you get a B-1/B-2 combination visa or a simple B-1 visa.
Note that "Fee: none" in the table linked above means that there is no additional "reciprocity" fee on top of the normal visa application fee, currently USD 160 for most nonimmigrant visas, including B visas.