That's a wide-open question. Depending on the chemistry, a single cell of a battery can have anywhere from about a volt to almost five volts. A group of cells is often connected together to make a higher voltage battery "pack" such as in a car, where six two-volt cells are connected in series to make 12 volts..
If you can give more detail I can give you a better answer. Do you need rechargeable or non-rechargeable (primary) batteries? How much current and voltage do you need? Are there other constraints, like size, weight, cost, longevity, flammability, etc?
AAs and AAAs are the most common alkaline batteries and output 1.2V nominally (but are around 1.5V when first used). Because AAs output 1.2V, you will need to combine them in packs of 3 or 4 to run your 3.3V or 5V system. 9V batteries are obviously 9V nominally.
