What does "prev_out" and "n" mean in blockchain.info's API data? When getting information about transactions with blockchain.info's API, every transaction contains exactly one "prev_out" object, and within that object "n" is always equal to either 0 or 1.

What do these things stand for/mean?
A transaction consists of a number of inputs and a number of outputs. Outputs define a script that need to be executed to be able to spend the coins in the output. Inputs provide data to enter into an output script to make it execute successfully and to spend the coins in it.

So, a transaction input must be able to reference the output it is willing to spend. Outputs in a transaction are ordered, so an output can be referred to by specifying the transaction ID of the transaction it has been defined in, and the index it has in the list of specified outputs in that transaction.

The prev_out field is the transaction hash (txid) and the n is the index of the output.

It's not true that every transaction contains exactly one prev_out value. However, many transactions do. This is because many transactions have only one input. You must know, though, that it is possible to have multiple inputs.