Botswana’s currency is called the pula, which is divided into 100 thebe. One US dollar is approximately ten pula and you can withdraw from automatic cash points in any large town.
Visa and MasterCard are widely accepted in urban areas, but away from the cities it’s best to carry cash. South African rands are accepted along Botswana’s southern border and can be used for fuel purchases in the nearby border towns. Further north you’ll need to carry pula. Keep enough for a full tank of fuel and some emergency supplies, and then use a credit card whenever possible. Top up with cash when you see a cash point and keep it in a safe place and out of sight at all times. Botswana is not a dangerous country at all, but always take the usual precautions.