Like most countries, Botswana has had a special set of entry requirements with respect to the coronavirus pandemic.
These requirements were lifted on 28 September 2022. There is now no requirement to present a vaccination certificate or proof of a negative PCR test to enter the country. Whilst in the country there is no longer any requirement to wear a mask or observe social distancing.
Note that this is just the official position. Local tourism businesses are free to adopt their own policies. Some accommodations and activities may require proof of vaccination, or ask you to sanitise your hands on arrival.
So if you have a vaccination card it may pay to bring it with you. And many local people are still wearing masks in indoor settings or on public transport. If you want to wear a mask yourself you won’t look at all out of the ordinary.